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Document And Entity Information - shares	3 Months Ended
Document And Entity Information - shares	Jul. 31, 2014	Aug. 31, 2014
Document and Entity Information [Abstract]
Entity Registrant Name	Ocean Power Technologies, Inc.
Document Type	10-Q
Current Fiscal Year End Date	--04-30
Entity Common Stock, Shares Outstanding		17,584,257
Amendment Flag	false
Entity Central Index Key	0001378140
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Well-known Seasoned Issuer	No
Document Period End Date	Jul. 31, 2014
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1

Consolidated Balance Sheets (Current Period Unaudited) - USD ($)	Jul. 31, 2014	Apr. 30, 2014
Current assets:
Cash and cash equivalents	$ 7,627,650	$ 13,858,659
Marketable securities	17,244,357	14,493,881
Restricted cash	6,537,037	6,124,960
Accounts receivable, net		308,731
Unbilled receivables	491,632	37,410
Other current assets	948,630	568,377
Total current assets	32,849,306	35,392,018
Property and equipment, net	285,450	317,513
Patents, net	621,224	828,298
Restricted cash	1,089,656	1,221,696
Other noncurrent assets	373,889	325,310
Total assets	35,219,525	38,084,835
Current liabilities:
Accounts payable	660,581	501,397
Accrued expenses	3,739,223	2,931,239
Advance payment received from customer	5,237,037	4,709,055
Unearned revenues		992,447
Current portion of long-term debt	100,000	100,000
Total current liabilities	9,736,841	9,234,138
Long-term debt	125,000	150,000
Deferred credits	600,000	600,000
Total liabilities	10,461,841	9,984,138
Commitments and contingencies (note 9)
Ocean Power Technologies, Inc. stockholders’ equity:
Preferred stock, $0.001 par value; authorized 5,000,000 shares, none issued or outstanding	0	0
Common stock, $0.001 par value; authorized 105,000,000 shares, issued 17,584,257 and 17,593,637 shares, respectively	17,584	17,594
Treasury stock, at cost; 38,658 and 37,852 shares, respectively	(132,016)	(130,707)
Additional paid-in capital	180,467,630	180,454,341
Accumulated deficit	(154,923,255)	(151,640,503)
Accumulated other comprehensive loss	(227,711)	(225,733)
Total Ocean Power Technologies, Inc. stockholders’ equity	25,202,232	28,474,992
Noncontrolling interest in Ocean Power Technologies (Australasia) Pty Ltd.	(444,548)	(374,295)
Total equity	24,757,684	28,100,697
Total liabilities and stockholders’ equity	$ 35,219,525	$ 38,084,835

Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - $ / shares	Jul. 31, 2014	Apr. 30, 2014
Preferred stock par value (in Dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock par value (in Dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	105,000,000	105,000,000
Common stock, shares issued	17,584,257	17,593,637
Treasury stock, shares	38,658	37,852

Consolidated Statements of Operations (Unaudited) - USD ($)	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Revenues	$ 1,540,528	$ 460,927
Cost of revenues	1,967,164	460,376
Gross (loss) profit	(426,636)	551
Operating expenses:
Product development (recoveries) costs	(80,055)	1,270,945
Selling, general and administrative costs	3,122,972	2,547,759
Total operating expenses	3,042,917	3,818,704
Operating loss	(3,469,553)	(3,818,153)
Interest (expense) income, net	(58,620)	358
Other income	185,000
Foreign exchange (loss) gain	(5,658)	21,770
Net loss	(3,348,831)	(3,796,025)
Less: Net loss attributable to the noncontrolling interest in Ocean Power Technologies (Australasia) Pty Ltd.	66,079	46,055
Net loss attributable to Ocean Power Technologies, Inc	$ (3,282,752)	$ (3,749,970)
Basic and diluted net loss per share (in Dollars per share)	$ (0.19)	$ (0.36)
Weighted average shares used to compute basic and diluted net loss per share (in Shares)	17,464,683	10,321,457

Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($)	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Net loss	$ (3,348,831)	$ (3,796,025)
Foreign currency translation adjustment	(6,152)	3,329
Total comprehensive loss	(3,354,983)	(3,792,696)
Comprehensive loss attributable to the noncontrolling interest in Ocean Power Technologies (Australasia) Pty Ltd.	70,253	23,936
Comprehensive loss attributable to Ocean Power Technologies, Inc	$ (3,284,730)	$ (3,768,760)

Consolidated Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Short-Term [Member]
Changes in operating assets and liabilities:
Unearned Revenues	$ (992,447)	$ (581,096)
Long-Term [Member]
Changes in operating assets and liabilities:
Unearned Revenues		284,749
Net loss	(3,348,831)	(3,796,025)
Foreign exchange loss (gain)	5,658	(21,770)
Depreciation and amortization	243,672	107,237
Treasury note premium amortization		5,392
Compensation expense related to stock option grants and restricted stock	12,639	229,655
Accounts receivable	308,731	472,480
Unbilled receivables	(454,222)	37,877
Other current assets	(378,606)	(224,240)
Other noncurrent assets	(46,816)	(35,344)
Accounts payable	153,812	562,092
Accrued expenses	800,888	(118,537)
Advanced payment from ARENA	527,982
Net cash used in operating activities	(3,167,540)	(3,077,530)
Cash flows from investing activities:
Purchases of marketable securities	(11,747,042)	(6,998,108)
Maturities of marketable securities	8,996,566	10,993,172
Restricted cash	(255,000)	100,000
Purchases of equipment	(1,041)	(14,522)
Net cash (used in) provided by investing activities	(3,006,517)	4,080,542
Cash flows from financing activities:
Common stock issuance costs	641
Repayment of debt	(25,000)	(25,000)
Acquisition of treasury stock	(1,309)	(6,814)
Net cash used in financing activities	(25,668)	(31,814)
Effect of exchange rate changes on cash and cash equivalents	(31,284)	(6,335)
Net (decrease) increase in cash and cash equivalents	(6,231,009)	964,863
Cash and cash equivalents, beginning of period	13,858,659	6,372,788
Cash and cash equivalents, end of period	7,627,650	7,337,651
Supplemental disclosure of noncash investing and financing activities:
Capitalized purchases of equipment financed through accounts payable and accrued expenses	$ 3,413	$ 1,590

Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($)	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Noncontrolling Interest [Member]	Total
Balance at Apr. 30, 2013	$ 10,403	$ (123,893)	$ 159,155,365	$ (140,671,311)	$ (79,786)	$ (169,521)	$ 18,121,257
Balance (in Shares) at Apr. 30, 2013	10,403,215	(33,771)
Net loss				(3,749,970)		(46,055)	(3,796,025)
Stock based compensation			220,109				220,109
Issuance (forfeiture) of restricted stock, net	$ (8)		9,546				9,538
Issuance (forfeiture) of restricted stock, net (in Shares)	(8,417)
Acquisition of treasury stock		$ (6,814)					$ (6,814)
Acquisition of treasury stock (in Shares)		(4,081)					(4,081)
Other comprehensive income (loss)					(18,790)	22,119	$ 3,329
Balance at Jul. 31, 2013	$ 10,395	$ (130,707)	159,385,020	(144,421,281)	(98,576)	(193,457)	14,551,394
Balance (in Shares) at Jul. 31, 2013	10,394,798	(37,852)
Balance at Apr. 30, 2014	$ 17,594	$ (130,707)	180,454,341	(151,640,503)	(225,733)	(374,295)	28,100,697
Balance (in Shares) at Apr. 30, 2014	17,593,637	(37,852)
Net loss				(3,282,752)		(66,079)	(3,348,831)
Stock based compensation			714				714
Issuance (forfeiture) of restricted stock, net	$ (10)		11,925				11,915
Issuance (forfeiture) of restricted stock, net (in Shares)	(9,380)
Acquisition of treasury stock		$ (1,309)					$ (1,309)
Acquisition of treasury stock (in Shares)		(806)					(806)
Sale of stock			650				$ 650
Other comprehensive income (loss)					(1,978)	(4,174)	(6,152)
Balance at Jul. 31, 2014	$ 17,584	$ (132,016)	$ 180,467,630	$ (154,923,255)	$ (227,711)	$ (444,548)	$ 24,757,684
Balance (in Shares) at Jul. 31, 2014	17,584,257	(38,658)

Note 1 - Background, Basis of Presentation and Liquidity

3 Months Ended

Jul. 31, 2014

Disclosure Text Block [Abstract]

Business Description and Basis of Presentation [Text Block]

(1) Background, Basis of Presentation and Liquidity

a)	Background

Ocean Power Technologies, Inc. (the “Company”) was incorporated in 1984 in New Jersey, commenced business operations in 1994 and re-incorporated in Delaware in 2007. The Company develops and is seeking to commercialize proprietary systems that generate electricity by harnessing the renewable energy of ocean waves. The Company markets its products in the United States and internationally. Since fiscal 2002, government agencies have accounted for a significant portion of the Company’s revenues. These revenues were largely for the support of product development efforts. The Company’s goal is that an increased portion of its revenues be from the sale of products and maintenance services, as compared to revenue to support its product development efforts. As the Company continues to advance its proprietary technologies, it expects to continue to have a net decrease in cash from operating activities unless and until it achieves positive cash flow from the planned commercialization of its products and services.

b)	Basis of Presentation

The accompanying unaudited consolidated financial statements have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by generally accepted accounting principles for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring adjustments) considered necessary for a fair presentation have been included. The interim operating results are not necessarily indicative of the results for a full year or for any other interim period. Further information on potential factors that could affect the Company's financial results can be found in the Company's Annual Report on Form 10-K for the year ended April 30, 2014 filed with the Securities and Exchange Commission (“SEC”) and elsewhere in this Form 10-Q.

c)	Liquidity

The Company has incurred net losses and negative operating cash flows since inception. As of July 31, 2014, the Company had an accumulated deficit of $154.9 million. As of July 31, 2014, the Company’s cash and cash equivalents and marketable securities balance was approximately $24.9 million. Based upon the Company’s cash and cash equivalents and marketable securities balance as of July 31, 2014, the Company believes that it will be able to finance its capital requirements and operations through at least the fourth calendar quarter of 2015. In addition, as of July 31, 2014, the Company’s restricted cash balance was approximately $7.6 million, which included $5.2 million that was subsequently paid to ARENA in August 2014. See Note 2(f).

During 2014 and 2013, the Company continued to make investments in ongoing product development efforts in anticipation of future growth. The Company’s future results of operations involve significant risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, risks from insufficiencies of capital, technology development, scalability of technology and production, dependence on skills of key personnel, concentration of customers and suppliers, performance of PowerBuoys, deployment risks and laws, regulations and permitting. In order to complete its future growth strategy, the Company will require additional equity and/or debt financing. There is no assurance that additional equity and/or debt financing will be available to the Company as needed. If sufficient financing is not obtained by the Company, we may be required to further curtail or limit certain product development costs, and/or selling, general and administrative activities in order to reduce our cash expenditures.

In June 2013, we established an at the market offering facility (the “ATM Facility”) with Ascendiant Capital Markets, LLC (the “Manager”) via an At the Market Offering Agreement (the “ATM Agreement”). Under the ATM Agreement, we offered and sold shares of our common stock from time to time through the Manager, acting as sales agent, in ordinary brokerage transactions at prevailing market prices. Under the ATM Facility, we issued 3,306,334 shares of our common stock at an average price to the public of $3.02 per share. Net proceeds from the ATM Facility were approximately $9,698,000 during fiscal 2014.

Also in fiscal 2014, we entered into an underwriting agreement (the “Underwriting Agreement”) with Roth Capital Partners, LLC (the “Underwriter”) on April 4, 2014, with respect to the issuance and sale in an underwritten public offering (the “Public Offering”) of an aggregate of 3,800,000 shares of our common stock at a price to the public of $3.10 per share. The Underwriting Agreement contained customary representations, warranties and agreements by us, customary conditions to closing and indemnification obligations, and a 90 day lock-up period that limited transactions in our common stock by us. Net proceeds from the Public Offering were approximately $10,828,000.

Form S-3 limits the aggregate market value of securities that we are permitted to offer in any 12-month period under Form S-3, whether under the ATM Agreement, the Underwriting Agreement or otherwise, to one third of our public float. Given the fiscal 2014 share sales, we fully utilized the ATM Agreement and reached the applicable limit under Form S-3. Of the $40 million authorized under the S-3 Shelf, approximately $18.2 million remains available for issuance. During the three months ended July 31, 2014 there were no proceeds from the sale of stock under the S-3 Shelf.

Note 2 - Summary of Significant Accounting Policies

3 Months Ended

Jul. 31, 2014

Accounting Policies [Abstract]

Significant Accounting Policies [Text Block]

(2) Summary of Significant Accounting Policies

(a) Consolidation and Cost Method Investment

The accompanying consolidated financial statements include the accounts of the Company and its majority-owned subsidiaries. All significant intercompany balances and transactions have been eliminated in consolidation. Participation of stockholders other than the Company in the net assets and in the earnings or losses of a consolidated subsidiary is reflected as a noncontrolling interest in the Company's Consolidated Balance Sheets and Statements of Operations, which adjusts the Company's consolidated results of operations to reflect only the Company's share of the earnings or losses of the consolidated subsidiary. As of July 31, 2014, there was one noncontrolling interest, consisting of 11.8% of the Company's Australian subsidiary, Ocean Power Technologies (Australasia) Pty. Ltd. (“OPTA”). OPTA owns 100% of Victorian Wave Partners Pty. Ltd. (“VWP”), which is also organized under the laws of Australia.

In addition, the Company evaluates its relationships with other entities to identify whether they are variable interest entities, and to assess whether it is the primary beneficiary of such entities. If the determination is made that the Company is the primary beneficiary, then that entity is included in the consolidated financial statements. As of July 31, 2014, there were no such entities.

(b) Use of Estimates

The preparation of the consolidated financial statements requires management of the Company to make a number of estimates and assumptions relating to the reported amounts of assets and liabilities and the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the period. Significant items subject to such estimates and assumptions include the recoverability of the carrying amount of property and equipment and patents; valuation allowances for receivables and deferred income tax assets; estimated costs to complete for projects; and percentage of completion of customer contracts for purposes of revenue recognition. Actual results could differ from those estimates. The current economic environment, particularly the macroeconomic pressures in certain European countries, has increased the degree of uncertainty inherent in those estimates and assumptions.

(c) Revenue Recognition

The Company’s contracts are either cost plus or fixed price contracts. Under cost plus contracts, customers are billed for actual expenses incurred plus an agreed-upon fee. Currently, the Company has two types of fixed price contracts, firm fixed price and cost-sharing. Under firm fixed price contracts, the Company receives an agreed-upon amount for providing products and services specified in the contract. Under cost-sharing contracts, the fixed amount agreed upon with the customer is only intended to fund a portion of the costs on a specific project.

Generally, the Company recognizes revenue using the percentage-of-completion method based on the ratio of costs incurred to total estimated costs at completion. In certain circumstances, revenue under contracts that have specified milestones or other performance criteria may be recognized only when the customer acknowledges that such criteria have been satisfied. In addition, recognition of revenue (and the related costs) may be deferred for fixed-price contracts until contract completion if the Company is unable to reasonably estimate the total costs of the project prior to completion. These contracts are subject to interpretation and management may make a judgment as to the amount of revenue earned and recorded. Because the Company has a small number of contracts, revisions to the percentage-of-completion determination, management interpretation or delays in meeting performance and contractual criteria or in completing projects may have a significant effect on revenue for the periods involved. Upon anticipating a loss on a contract, the Company recognizes the full amount of the anticipated loss in the current period.

Under cost plus and firm fixed price contracts, a profit or loss on a project is recognized depending on whether actual costs are more or less than the agreed upon amount. Under cost sharing contracts, an amount corresponding to the revenue is recorded in cost of revenues, resulting in gross profit on these contracts of zero. The Company’s share of the costs is recorded as product development expense.

Unbilled receivables represent expenditures on contracts, plus applicable profit margin, not yet billed. Unbilled receivables are normally billed and collected within one year. Billings made on contracts are recorded as a reduction of unbilled receivables, and to the extent that such billings and cash collections exceed costs incurred plus applicable profit margin, they are recorded as unearned revenues.

Most of the Company’s projects are under cost-sharing contracts.

(d) Cash and Cash Equivalents

Cash equivalents consist of investments in short-term financial instruments with initial maturities of three months or less from the date of purchase. Cash and cash equivalents include the following:

	July 31, 2014		April 30, 2014

Checking and savings accounts	$	2,334,140	$	1,917,176
Certificates of deposits and US Treasury obligations		4,749,924		11,499,768
Money market funds		543,586		441,715
	$	7,627,650	$	13,858,659

(e) Marketable Securities

Marketable securities with original maturities longer than three months but that mature in less than one year from the balance sheet date are classified as current assets. Marketable securities that mature more than one year from the balance sheet date are classified as noncurrent assets. Marketable securities that the Company has the intent and ability to hold to maturity are classified as investments held-to-maturity and are reported at amortized cost. The difference between the acquisition cost and face values of held-to-maturity investments is amortized over the remaining term of the investments and added to or subtracted from the acquisition cost and interest income. As of July 31, 2014 and April 30, 2014, all of the Company’s investments were classified as held-to-maturity.

(f) Restricted Cash and Credit Facility

A portion of the Company’s cash is restricted under the terms of three security agreements.

One agreement is between Ocean Power Technologies, Inc. and Barclays Bank. Under this agreement, the cash is on deposit at Barclays Bank and serves as security for letters of credit that are expected to be issued by Barclays Bank on behalf of OPT LTD one of the Company's subsidiaries, under an €800,000 ($964,656) credit facility established by Barclays Bank for OPT LTD. The credit facility is for the issuance of letters of credit and bank guarantees and carries a fee of 1% per annum of the amount of any such obligations issued by Barclays Bank. As of July 31, 2014, there were €278,892 ($373,660) in letters of credit outstanding under this agreement. The credit facility does not have an expiration date, but is cancelable at the discretion of the bank.

The second agreement is between Ocean Power Technologies, Inc. and the New Jersey Board of Public Utilities (NJBPU). The Company received a $500,000 recoverable grant award from the NJBPU. Under this arrangement, the Company annually assigns to the NJBPU a certificate of deposit in an amount equal to the outstanding grant balance. See Note 6.

The third agreement concerns three letters of credit issued by Ocean Power Technologies, Inc. for the benefit of the Oregon Department of State Lands. The three letters of credit relate to the removal of certain of the Company’s anchoring and mooring equipment from the seabed off the coast of Oregon. These letters of credit are secured by certificates of deposit with PNC Bank and total $1,200,000. All such letters of credit have a term through October 29, 2014.

The Company has classified the initial grant funding received from the Australian Renewable Energy Agency (“ARENA”) of A$5,595,723 ($5,237,037), which includes an amount required to be submitted as goods and services tax (GST), as restricted cash.

During the three months ended July 31, 2014, the Company remitted the GST in the amount of A$508,702 ($476,094) to the Australian Tax Office (ATO) in accordance with local tax laws. This amount will be reclaimed from the ATO and is recorded in other current assets as of July 31, 2014. Subsequent to July 31, 2014, the Company returned the initial grant funding received of A$5,595,723 ($5,237,037) and interest of A$109,051 ($102,061) to ARENA in accordance with the Deed Of Variation and Termination of Funding Deed executed between the parties in August 2014.

	July 31, 2014		April 30, 2014
Current:
Australian Renewable Energy Agency (ARENA)	$	5,237,037	$	5,179,960
NJBPU agreement		100,000		100,000
Oregon Department of State Lands		1,200,000		845,000
	$	6,537,037	$	6,124,960

	July 31, 2014		April 30, 2014
Long Term:
Barclay's Bank Agreement	$	964,656	$	996,696
NJBPU agreement		125,000		225,000
	$	1,089,656	$	1,221,696

(g) Foreign Exchange Gains and Losses

The Company has invested in certain certificates of deposit and has maintained cash accounts that are denominated in British pounds sterling, Euros and Australian dollars. These amounts are included in cash, cash equivalents, restricted cash and marketable securities on the accompanying consolidated balance sheets. Such positions may result in realized and unrealized foreign exchange gains or losses from exchange rate fluctuations, which gains and losses are included in foreign exchange loss in the accompanying consolidated statements of operations.

	Three Months Ended July 31,
	2014			2013

Foreign exchange (loss) gain	$	(5,658	)	$	21,770

Foreign currency denominated certificates of deposit and cash accounts:

	July 31, 2014		April 30, 2014

Restricted	$	6,201,693	$	6,176,656
Unrestricted		423,175		1,232,111
	$	6,624,868	$	7,408,767

(h) Long-Lived Assets

Long-lived assets, such as property and equipment and patents subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of the asset may not be recoverable. Recoverability of assets to be held and used is measured by a comparison of the carrying amount of the asset to estimated undiscounted future cash flows expected to be generated by the asset. If the carrying amount of the asset exceeds its estimated future cash flows, then an impairment charge is recognized in the amount by which the carrying amount of the asset exceeds the fair value of the asset. During the three months ended July 31, 2014, the Company reviewed its long-lived assets for impairment and estimated that the remaining useful lives, for purposes of amortizing capitalized external patent costs, should be reduced from approximately five years to one year.

(i) Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentration of credit risk consist principally of cash balances, bank certificates of deposit and trade receivables. The Company invests its excess cash in highly liquid investments (principally, short-term bank deposits, Treasury bills, Treasury notes and money market funds) and does not believe that it is exposed to any significant risks related to its cash accounts, money market funds or certificates of deposit.

The table below shows the percentage of the Company's revenues derived from customers whose revenues accounted for at least 10% of the Company's consolidated revenues for at least one of the periods indicated:

	Three months ended July 31,
Customer	2014			2013

European Union (WavePort project)		62	%		35	%
Mitsui Engineering & Shipbuilding		31	%	―
US Department of Energy		7	%		26	%
UK Government's Technology Strategy Board	―				38	%
		100	%		99	%

The loss of, or a significant reduction in revenues from, any of the current customers could significantly impact the Company's financial position or results of operations. The Company does not require its customers to maintain collateral.

(j) Net Loss per Common Share

Basic and diluted net loss per share for all periods presented is computed by dividing net loss by the weighted average number of shares of common stock outstanding during the period. Due to the Company's net losses, potentially dilutive securities, consisting of outstanding stock options and non-vested performance-based shares, were excluded from the diluted loss per share calculation due to their anti-dilutive effect.

In computing diluted net loss per share, options to purchase shares of common stock and non-vested restricted stock issued to employees and non-employee directors, totaling 1,087,649 for the three months ended July 31, 2014, and 1,290,274 for the three months ended July 31, 2013, were excluded from the computations as the effect would be anti-dilutive due to the Company's losses.

(k)Recently Issued Accounting Standards

On May 28, 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers, which requires an entity to recognize the amount of revenue to which it expects to be entitled for the transfer of promised goods or services to customers. The ASU will replace most existing revenue recognition guidance in U.S. Generally Accepted Accounting Principles (“GAAP”) when it becomes effective. The new standard is effective for us on January 1, 2017. Early application is not permitted. The standard permits the use of either the retrospective or the cumulative effect transition method. We are evaluating the effect that ASU 2014-09 will have on our consolidated financial statements and related disclosures. We have not yet selected a transition method nor have we determined the effect of the standard on our ongoing financial reporting.

Note 3 - Marketable Securities

3 Months Ended

Jul. 31, 2014

Investments, Debt and Equity Securities [Abstract]

Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block]

(3) Marketable Securities

Marketable securities with initial maturities longer than three months but that mature within one year from the balance sheet date are classified as current assets and are summarized as follows:

July 31,

2014

April 30,

2014

US Treasury obligations

17,244,357

14,493,881

- Definition

The entire disclosure for investments in certain debt and equity securities.

+ References + Details

Note 4 - Balance Sheet Detail

3 Months Ended

Jul. 31, 2014

Disclosure Text Block Supplement [Abstract]

Supplemental Balance Sheet Disclosures [Text Block]

(4) Balance Sheet Detail

	July 31, 2014			April 30, 2014

Accounts receivable, net
Accounts receivable	$	―		$	308,731
Allowance for doubtful accounts		―		―
	$	―		$	308,731

Patents
Patents	$	1,536,029		$	1,536,029
Accumulated amortization		(914,805	)		(707,731	)
	$	621,224		$	828,298


Accrued expenses
Project costs	$	1,260,217		$	1,263,293
Contract loss reserve		254,186		―
Employee incentive payments		490,118			310,370
Accrued salary and benefits		476,297			455,909
Legal and accounting fees		938,195			168,402
Goods and services tax (GST) due to Australian Tax Office	―				470,905
Other		320,210			262,360
	$	3,739,223		$	2,931,239

Note 5 - Related Party Transactions

3 Months Ended

Jul. 31, 2014

(5) Related Party Transactions

	Three Months Ended July 31,
	2014		2013
Related party consulting expense	$	113,813	$	―

In April 2014, the Company entered into an Executive Transition Agreement with George W. Taylor, who was formerly employed by the Company as Executive Vice Chairman and served on the Company’s Board of Directors prior to that date. Under this agreement, Dr. Taylor will receive up to fifteen months of consulting fees at a monthly rate of $20,000. For the three months ended July 31, 2014, the Company recorded $60,000 in expense relating to this agreement.

In June 2014, the Company entered into an agreement with David L. Keller, who has served as a non-executive director of the Company since October 2013. Under this agreement, Mr. Keller serves as Interim Chief Executive Officer effective with the June 9, 2014 termination of the Company’s former Chief Executive Officer, Charles F. Dunleavy. Mr. Keller will continue in this position while the Company searches for a permanent replacement and will receive a consulting fee of $1,500 per day of services provided. For the three months ended July 31, 2014, the Company recorded $53,813 in expense relating to this agreement.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References + Details

Note 6 - Debt

3 Months Ended

Jul. 31, 2014

Debt Disclosure [Abstract]

Debt Disclosure [Text Block]

(6) Debt

The Company was awarded a recoverable grant totaling $500,000 from the NJBPU under the Renewable Energy Business Venture Assistance Program. Under the terms of this agreement, the amount to be repaid is a fixed monthly amount of principal only, repayable over a five-year period beginning in November 2011. The terms also required the Company to assign to the NJBPU a certificate of deposit in an amount equal to the outstanding grant balance. See Note 2(f).

	July 31, 2014			April 30, 2014

Total debt	$	225,000		$	250,000
Current portion of long-term debt		(100,000	)		(100,000	)
Long-term debt	$	125,000		$	150,000

Note 7 - Deferred Credits Payable

3 Months Ended

Jul. 31, 2014

Customer Advances And Deposits Disclosure [Text Block] [Abstract]

Customer Advances And Deposits Disclosure [Text Block]

(7) Deferred Credits Payable

During the year ended April 30, 2001, in connection with the sale of common stock to an investor, the Company received $600,000 from the investor in exchange for an option to purchase up to 500,000 metric tons of carbon emissions credits generated by the Company during the years 2008 through 2012, at a 30% discount from the then-prevailing market rate. If the Company received emission credits under applicable laws and failed to sell to the investor the credits up to the full amount of emission credits covered by the option, the investor was entitled to liquidated damages equal to 30% of the aggregate market value of the shortfall in emission credits (subject to a limit on the market price of emission credits). Under the terms of the agreement, if the Company did not become entitled under applicable laws to the full amount of emission credits covered by the option by December 31, 2012, the Company was obligated to return the option fee of $600,000, less the aggregate discount on any emission credits sold to the investor prior to such date. In December 2012, the Company and the investor agreed to extend the period for the sale of emission credits until December 31, 2017. As of July 31, 2014, the Company has not generated any emissions credits eligible for purchase under the agreement. The $600,000 has been classified as a noncurrent liability as of July 31, 2014.

Note 8 - Stock-Based Compensation

3 Months Ended

Jul. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Disclosure of Compensation Related Costs, Share-based Payments [Text Block]

(8) Stock-Based Compensation

The decrease in stock-based compensation costs was related primarily to the termination for cause of Charles F. Dunleavy, Chief Executive Officer, on June 9, 2014. In accordance with the Company’s 2001 Stock Plan and the 2006 Stock Incentive Plan, all vested and unvested grants are forfeited. In addition, the Company did not issue any stock-based awards during the three months ended July 31, 2014. The aggregate stock-based compensation expense related to all stock-based transactions recorded in the consolidated statements of operations was approximately $13,000 and $230,000 for the three months ended July 31, 2014 and 2013, respectively.

(a) Stock Options

Valuation Assumptions for Options Granted During the Three Months Ended July 31, 2014 and 2013

The fair value of each stock option granted, for both service-based and performance-based vesting requirements, during the three months ended July 31, 2013 was estimated at the date of grant using the Black-Scholes option pricing model, assuming no dividends and using the weighted average valuation assumptions noted in the following table. The risk-free rate is based on the US Treasury yield curve in effect at the time of grant. The expected life (estimated period of time outstanding) of the stock options granted was estimated using the "simplified" method as permitted by the SEC's Staff Accounting Bulletin No. 107, Share-Based Payment. Expected volatility was based on the Company’s historical volatility for the three months ended July 31, 2013. There were no stock options granted during the three months ended July 31, 2014.

	Three Months Ended July 31,
	2014		2013
Risk-free interest rate		—		1.6	%
Expected dividend yield		—		0.0	%
Expected life (in years)		—		6.3
Expected volatility		—		74.61	%

The above assumptions were used to determine the weighted average per share fair value of $1.12 for stock options granted during the three months ended July 31, 2013.

A summary of stock options under the plans is as follows:

						Weighted
						Average
				Weighted		Remaining
	Shares			Average		Contractual
	Underlying			Exercise		Term
	Options			Price		(In Years)
Outstanding as of April 30, 2014		1,472,292		$	5.53		5.9
Forfeited		(462,251	)		7.21
Exercised		—			—
Granted		—			—
Outstanding as of July 31, 2014		1,010,041			4.77		5.8
Exercisable as of July 31, 2014		676,838			6.32		4.4

As of July 31, 2014, the total intrinsic value of outstanding and exercisable options was $0. As of July 31, 2014, approximately 328,000 additional options are expected to vest in the future, which options had no intrinsic value and a weighted average remaining contractual term of 8.7 years. There was approximately $1,000 and $220,000 of total recognized compensation cost related to stock options for the three months ended July 31, 2014 and 2013, respectively. As of July 31, 2014, there was approximately $235,000 of total unrecognized compensation cost related to non-vested stock options granted under the plans. This cost is expected to be recognized over a weighted-average period of 2.5 years. The Company normally issues new shares to satisfy option exercises under these plans. During the three months ended July 31, 2014, there were no stock options granted. Stock options outstanding as of July 31, 2014 included 115,786 stock options subject to performance-based vesting requirements.

(b) Restricted Stock

Compensation expense for non-vested restricted stock was historically recorded based on its market value on the date of grant and recognized over the associated service and performance period. During the three months ended July 31, 2014, there were no shares granted to employees. During the three months ended July 31, 2014, 9,380 shares of non-vested restricted stock subject to performance-based vesting requirements were forfeited in accordance with performance objectives. Restricted stock issued and unvested at July 31, 2014 included 37,329 shares of non-vested restricted stock subject to performance-based vesting requirements.

A summary of non-vested restricted stock under the plans is as follows:

				Weighted
	Number			Average Price per
	of Shares			Share

Issued and unvested at April 30, 2014		97,610		$	2.23
Granted	—			—
Forfeited		(9,380	)		2.30
Vested		(10,622	)		2.36
Issued and unvested at July 31, 2014		77,608			2.21

There was approximately $12,000 and $10,000 of total recognized compensation cost related to restricted stock for the three months ended July 31, 2014 and 2013, respectively. As of July 31, 2014, there was approximately $63,000 of total unrecognized compensation cost related to non-vested restricted stock granted under the plans. This cost is expected to be recognized over a weighted average period of 1.9 years.

(c)Treasury Stock

During the three months ended July 31, 2014 and 2013, 806 and 4,081 shares, respectively, of common stock were purchased by the Company from employees to pay taxes related to the vesting of restricted stock.

Note 9 - Commitments and Contingencies

3 Months Ended

Jul. 31, 2014

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies Disclosure [Text Block]

(9) Commitments and Contingencies

(a) Litigation

Shareholder Litigation:

The Company is a defendant in four putative securities class actions pending in the United States District Court for the District of New Jersey. See Roby v. Ocean Power Technologies, Inc., et al., Case No. 3:14-cv-03799-FLW-LHG; Chew, et al. v. Ocean Power Technologies, Inc. et. al., Case No 3:14-cv-03815-MAS-DEA; Konstantinidis v. Ocean Power Technologies, Inc., et al., Case No. 3:14-cv-04015-FLW-DEA; Turner v. Ocean Power Technologies, Inc., et al., Case No. 3:14-cv-04592. The Company’s former Chief Executive Officer is named as a defendant in each of the lawsuits and the Company’s Chief Financial Officer is named as a defendant in two of the lawsuits. The complaints allege claims for violations of §10(b) and §20(a) of the Securities Exchange Act of 1934 arising out of public statements relating to a now terminated agreement between Victorian Wave Partners Pty. Ltd. and the Australian Renewable Energy Agency for the development of a wave power station (the “VWP Project”). All four complaints seek unspecified monetary damages and other relief. On August 12, 2014, five motions for appointment of lead plaintiff were filed. The motions also seek to consolidate the actions. The Court has not ruled on the motions. The cases are still in their preliminary stages and defendants have not yet responded to the complaints.

On July 10, 2014, the Company received a demand letter (“Demand Letter”) from an attorney claiming to represent a shareholder demanding that the Company’s Board of Directors establish an independent committee to investigate and remedy alleged breaches of fiduciary duties by the Board of Directors and management relating to the VWP Project.

The Company also received a letter, dated August 19, 2014, (the “Section 220 Demand”) from another attorney claiming to represent a shareholder demanding, pursuant to 8 Del. C. § 220, to inspect certain books and records of the Company relating to the VWP Project and the termination of Charles Dunleavy as the Company’s Chief Executive Officer. The Company has not yet responded to the Section 220 Demand.

Employment Litigation:

On June 10, 2014, the Company announced that it had terminated Charles Dunleavy as Chief Executive Officer and as an employee of the Company, effective June 9, 2014, and that Mr. Dunleavy had also been removed from his position as Chairman of the Board of Directors. On June 17, 2014, Mr. Dunleavy wrote to the Company stating that he had retained counsel to represent him in connection with an alleged wrongful termination of his employment. On July 28, 2014, Mr. Dunleavy resigned from the Board and the boards of directors of the Company’s subsidiaries. To the Company’s knowledge, as of the date of filing of this Quarterly Report on Form 10-Q, Mr. Dunleavy has not filed any claims against the Company.

In addition, the Company is involved from time to time in certain legal actions arising in the ordinary course of business.

(b) Spain IVA (sales tax)

The Company received notice that the Spanish tax authorities are inquiring into its 2010 IVA (value-added tax) filing for which the Company benefitted from the offset of approximately $250,000 of input tax. The Company believes that the inquiry will find that the tax credit was properly claimed and, therefore, no liability has been recorded. The Company issued two letters of credit in the amount of €278,828 ($373,574) at the request of the Spanish tax authorities. This is a customary request during the inquiry period.

Note 10 - Income Taxes

3 Months Ended

Jul. 31, 2014

Income Tax Disclosure [Abstract]

Income Tax Disclosure [Text Block]

(10) Income Taxes

The Company did not recognize any consolidated income tax benefit (expense) for the three month periods ended July 31, 2014 and 2013. The Company has recorded a valuation allowance to reduce its net deferred tax asset to an amount that is more likely than not to be realized in future years. Accordingly, the benefit of the net operating loss that would have been recognized was offset by changes in the valuation allowance.

During the three months ended July 31, 2014, the Company had no material changes in uncertain tax positions.

Note 11 - Operating Segments and Geographic Information

3 Months Ended

Jul. 31, 2014

Segment Reporting [Abstract]

Segment Reporting Disclosure [Text Block]

(10) Operating Segments and Geographic Information

The Company views its business as one segment, which is the development of its PowerBuoy product for wave energy applications. The Company operates on a worldwide basis with one operating company in the US, one operating subsidiary in the UK and one operating subsidiary in Australia, which are categorized below as North America, Europe, and Asia and Australia, respectively. Revenues are generally attributed to the operating unit that bills the customers.

Geographic information is as follows:

	North America			Europe			Asia and Australia			Total

Three months ended July 31, 2014
Revenues from external customers	$	1,540,528		$	—		$	—		$	1,540,528
Operating loss		(2,582,613	)		(392,868	)		(494,072	)		(3,469,553	)

Three months ended July 31, 2013
Revenues from external customers		287,752			173,175			—			460,927
Operating loss		(3,122,599	)		(315,402	)		(380,152	)		(3,818,153	)


July 31, 2014
Long-lived assets		275,993			9,457			—			285,450
Total assets		28,718,561			769,569			5,731,395			35,219,525

April 30, 2014
Long-lived assets		305,314			12,024			175			317,513
Total assets	$	31,313,240		$	1,003,205		$	5,768,390		$	38,084,835

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 34
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 280
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8933-108599

Reference 7: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 26
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e8844-108599

Reference 8: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
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Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9031-108599

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Section 50
-Paragraph 42
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-Name Accounting Standards Codification
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-Paragraph 10
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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Reference 13: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 14: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Note 12 - Subsequent Event

3 Months Ended

Jul. 31, 2014

Subsequent Events [Abstract]

Subsequent Events [Text Block]

(11) Subsequent Event

Australia

In 2009, Leighton Contractors Pty. Ltd. (Leighton), formed Victorian Wave Partners Pty Ltd (“VWP”), a special purpose company for the development of a wave power project off the coast of Victoria, Australia. In 2010, VWP and the Commonwealth of Australia entered into an Energy Demonstration Program Funding Deed (“Funding Deed”), wherein VWP was awarded an A$66.5 million (approximately US$62 million) grant for the wave power project; however, receipt of funds under the grant was subject to certain terms, including achievement of future significant external funding milestones. The grant was expected to be used towards the A$232 million proposed cost of building and deploying a wave power station off the coast of Australia (the “Project”). In March 2012, our Australian subsidiary Ocean Power Technologies (Australasia) Pty. Ltd acquired 100% ownership of VWP from Leighton. In January 2014, VWP signed a Deed of Variation with the Australian Renewable Energy Agency (“ARENA”) that amended the Funding Deed, and, in March 2014, received the initial portion of the grant from ARENA in the amount of approximately A$5.6 million (approximately US$5.2 million) (the “Initial Funding”). The Initial Funding was subject to claw-back provisions if certain contractual requirements, including performance criteria, were not satisfied. In light of the claw-back provisions, the Company determined to classify the Initial Funding as an advance payment, hold the funds as restricted cash and defer recognition of the funds as revenue.

Public Statement of the Special Committee coincident with the completion of its investigation

On September 9, 2014, the Special Committee of the Board of Directors of Ocean Power Technologies, Inc. (OPT) completed its internal investigation into the commercial agreement between Victorian Wave Partners Ltd., an indirect consolidated subsidiary of OPT, and the Australian Renewable Energy Agency, including related public statements concerning a proposed wave power demonstration project off the coast of Victoria, Australia. The findings of the Special Committee are contained in the Form 8-k disclosure made on July 29, 2014, and no additional findings have been made. Therefore, the Special Committee has recommended that the Board of Directors dissolve the Special Committee at its next regular meeting after the Annual General Meeting of Shareholders scheduled for October 2, 2014.

In July 2014, VWP’s Board of Directors concluded that the wave power demonstration project contemplated was no longer commercially viable, and VWP delivered a termination notice to ARENA. In August 2014, the Company and ARENA executed the Deed of Variation and Termination of Funding Deed. Under this agreement the Company returned the initial grant funding received of A$5,595,723 ($5,237,037) and interest of A$109,051 ($102,061).

Shareholder Litigation:

FINRA Inquiry:

In August 2014, the Company provided documents to the Financial Industry Regulatory Authority (FINRA) in response to a July 9, 2014 request under NASDAQ Listing Rule 5250(a)(1) seeking information related to the internal investigation of the Special Committee of the Board of Directors. There are no outstanding requests to the Company from FINRA or any other regulators at this time.

Accounting Policies, by Policy (Policies)

3 Months Ended

Jul. 31, 2014

Accounting Policies [Abstract]

Basis of Accounting, Policy [Policy Text Block]

Basis of Presentation

Liquidity Disclosure [Policy Text Block]

Liquidity

Consolidation, Policy [Policy Text Block]

Consolidation and Cost Method Investment

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

Revenue Recognition, Policy [Policy Text Block]

Revenue Recognition

Most of the Company’s projects are under cost-sharing contracts.

Cash and Cash Equivalents, Policy [Policy Text Block]

Cash and Cash Equivalents

Cash equivalents consist of investments in short-term financial instruments with initial maturities of three months or less from the date of purchase. Cash and cash equivalents include the following:

	July 31, 2014		April 30, 2014

Checking and savings accounts	$	2,334,140	$	1,917,176
Certificates of deposits and US Treasury obligations		4,749,924		11,499,768
Money market funds		543,586		441,715
	$	7,627,650	$	13,858,659

Marketable Securities, Policy [Policy Text Block]

Marketable Securities

Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]

Restricted Cash and Credit Facility

A portion of the Company’s cash is restricted under the terms of three security agreements.

	July 31, 2014		April 30, 2014
Current:
Australian Renewable Energy Agency (ARENA)	$	5,237,037	$	5,179,960
NJBPU agreement		100,000		100,000
Oregon Department of State Lands		1,200,000		845,000
	$	6,537,037	$	6,124,960

	July 31, 2014		April 30, 2014
Long Term:
Barclay's Bank Agreement	$	964,656	$	996,696
NJBPU agreement		125,000		225,000
	$	1,089,656	$	1,221,696

Foreign Currency Transactions and Translations Policy [Policy Text Block]

Foreign Exchange Gains and Losses

	Three Months Ended July 31,
	2014			2013

Foreign exchange (loss) gain	$	(5,658	)	$	21,770

Foreign currency denominated certificates of deposit and cash accounts:

	July 31, 2014		April 30, 2014

Restricted	$	6,201,693	$	6,176,656
Unrestricted		423,175		1,232,111
	$	6,624,868	$	7,408,767

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Long-Lived Assets

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Concentration of Credit Risk

	Three months ended July 31,
Customer	2014			2013

European Union (WavePort project)		62	%		35	%
Mitsui Engineering & Shipbuilding		31	%	―
US Department of Energy		7	%		26	%
UK Government's Technology Strategy Board	―				38	%
		100	%		99	%

Earnings Per Share, Policy [Policy Text Block]

Net Loss per Common Share

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Issued Accounting Standards

Note 2 - Summary of Significant Accounting Policies (Tables)

3 Months Ended

Jul. 31, 2014

Accounting Policies [Abstract]

Schedule of Cash and Cash Equivalents [Table Text Block]

	July 31, 2014		April 30, 2014

Checking and savings accounts	$	2,334,140	$	1,917,176
Certificates of deposits and US Treasury obligations		4,749,924		11,499,768
Money market funds		543,586		441,715
	$	7,627,650	$	13,858,659

Schedule of Restricted Cash and Cash Equivalents [Table Text Block]

	July 31, 2014		April 30, 2014
Current:
Australian Renewable Energy Agency (ARENA)	$	5,237,037	$	5,179,960
NJBPU agreement		100,000		100,000
Oregon Department of State Lands		1,200,000		845,000
	$	6,537,037	$	6,124,960

	July 31, 2014		April 30, 2014
Long Term:
Barclay's Bank Agreement	$	964,656	$	996,696
NJBPU agreement		125,000		225,000
	$	1,089,656	$	1,221,696

Schedule of Foreign Exchange Gain (Loss) [Table Text Block]

	Three Months Ended July 31,
	2014			2013

Foreign exchange (loss) gain	$	(5,658	)	$	21,770

Schedule Of Foreign Currency Denominated Certificates of Deposit and Cash Accounts [Table Text Block]

	July 31, 2014		April 30, 2014

Restricted	$	6,201,693	$	6,176,656
Unrestricted		423,175		1,232,111
	$	6,624,868	$	7,408,767

Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block]

	Three months ended July 31,
Customer	2014			2013

European Union (WavePort project)		62	%		35	%
Mitsui Engineering & Shipbuilding		31	%	―
US Department of Energy		7	%		26	%
UK Government's Technology Strategy Board	―				38	%
		100	%		99	%

Note 3 - Marketable Securities (Tables)

3 Months Ended

Jul. 31, 2014

Current [Member]

Note 3 - Marketable Securities (Tables) [Line Items]

Marketable Securities [Table Text Block]

July 31,

2014

April 30,

2014

US Treasury obligations

17,244,357

14,493,881

Note 4 - Balance Sheet Detail (Tables)

3 Months Ended

Jul. 31, 2014

Disclosure Text Block Supplement [Abstract]

Schedule of Other Assets and Other Liabilities [Table Text Block]

	July 31, 2014			April 30, 2014

Accounts receivable, net
Accounts receivable	$	―		$	308,731
Allowance for doubtful accounts		―		―
	$	―		$	308,731

Patents
Patents	$	1,536,029		$	1,536,029
Accumulated amortization		(914,805	)		(707,731	)
	$	621,224		$	828,298


Accrued expenses
Project costs	$	1,260,217		$	1,263,293
Contract loss reserve		254,186		―
Employee incentive payments		490,118			310,370
Accrued salary and benefits		476,297			455,909
Legal and accounting fees		938,195			168,402
Goods and services tax (GST) due to Australian Tax Office	―				470,905
Other		320,210			262,360
	$	3,739,223		$	2,931,239

Note 5 - Related Party Transactions (Tables)

3 Months Ended

Jul. 31, 2014

	Three Months Ended July 31,
	2014		2013
Related party consulting expense	$	113,813	$	―

Note 6 - Debt (Tables)

3 Months Ended

Jul. 31, 2014

Debt Disclosure [Abstract]

Schedule of Debt [Table Text Block]

	July 31, 2014			April 30, 2014

Total debt	$	225,000		$	250,000
Current portion of long-term debt		(100,000	)		(100,000	)
Long-term debt	$	125,000		$	150,000

Note 8 - Stock-Based Compensation (Tables)

3 Months Ended

Jul. 31, 2014

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Three Months Ended July 31,
	2014		2013
Risk-free interest rate		—		1.6	%
Expected dividend yield		—		0.0	%
Expected life (in years)		—		6.3
Expected volatility		—		74.61	%

Schedule of Share-based Compensation, Activity [Table Text Block]

						Weighted
						Average
				Weighted		Remaining
	Shares			Average		Contractual
	Underlying			Exercise		Term
	Options			Price		(In Years)
Outstanding as of April 30, 2014		1,472,292		$	5.53		5.9
Forfeited		(462,251	)		7.21
Exercised		—			—
Granted		—			—
Outstanding as of July 31, 2014		1,010,041			4.77		5.8
Exercisable as of July 31, 2014		676,838			6.32		4.4

Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block]

				Weighted
	Number			Average Price per
	of Shares			Share

Issued and unvested at April 30, 2014		97,610		$	2.23
Granted	—			—
Forfeited		(9,380	)		2.30
Vested		(10,622	)		2.36
Issued and unvested at July 31, 2014		77,608			2.21

Note 11 - Operating Segments and Geographic Information (Tables)

3 Months Ended

Jul. 31, 2014

Segment Reporting [Abstract]

Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]

	North America			Europe			Asia and Australia			Total

Three months ended July 31, 2014
Revenues from external customers	$	1,540,528		$	—		$	—		$	1,540,528
Operating loss		(2,582,613	)		(392,868	)		(494,072	)		(3,469,553	)

Three months ended July 31, 2013
Revenues from external customers		287,752			173,175			—			460,927
Operating loss		(3,122,599	)		(315,402	)		(380,152	)		(3,818,153	)


July 31, 2014
Long-lived assets		275,993			9,457			—			285,450
Total assets		28,718,561			769,569			5,731,395			35,219,525

April 30, 2014
Long-lived assets		305,314			12,024			175			317,513
Total assets	$	31,313,240		$	1,003,205		$	5,768,390		$	38,084,835

Note 1 - Background, Basis of Presentation and Liquidity (Details)			3 Months Ended	12 Months Ended
	Aug. 08, 2014 USD ($)	Aug. 08, 2014 AUD ($)	Jul. 31, 2014 USD ($)	Apr. 30, 2014 USD ($) $ / shares shares
Proceeds From S-3 Shelf For Period [Member]
Note 1 - Background, Basis of Presentation and Liquidity (Details) [Line Items]
Proceeds from Issuance of Common Stock			$ 0
Subsequent Event [Member]
Note 1 - Background, Basis of Presentation and Liquidity (Details) [Line Items]
Repayments of Grant Funding	$ 5,237,037	$ 5,595,723
ATM Facility [Member]
Note 1 - Background, Basis of Presentation and Liquidity (Details) [Line Items]
Stock Issued During Period, Shares, New Issues (in Shares) \| shares				3,306,334
Share Price (in Dollars per share) \| $ / shares				$ 3.02
Proceeds from Issuance of Common Stock				$ 9,698,000
Underwriting Agreement [Member]
Note 1 - Background, Basis of Presentation and Liquidity (Details) [Line Items]
Stock Issued During Period, Shares, New Issues (in Shares) \| shares				3,800,000
Share Price (in Dollars per share) \| $ / shares				$ 3.10
Proceeds from Issuance of Common Stock				$ 10,828,000
Retained Earnings (Accumulated Deficit)			(154,923,255)	(151,640,503)
Cash, Cash Equivalents, And Marketable Securities			24,900,000
Restricted Cash and Cash Equivalents			$ 7,600,000
Shelf Registration Authorized Amount				40,000,000
Shelf Registration Amount Remaining of Offering Amount				$ 18,200,000

Note 2 - Summary of Significant Accounting Policies (Details)	Jul. 31, 2014 USD ($)	Jul. 31, 2014 AUD ($)	Mar. 31, 2014 USD ($)	Mar. 31, 2014 AUD ($)
Grant Funding [Member]
Note 2 - Summary of Significant Accounting Policies (Details) [Line Items]
Restricted Cash and Cash Equivalents	$ 5,237,037	$ 5,595,723	$ 5,200,000	$ 5,600,000

Note 2 - Summary of Significant Accounting Policies (Details) - Cash and Cash Equivalents - USD ($)	Jul. 31, 2014	Apr. 30, 2014
Checking and Savings Accounts [Member]
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	$ 2,334,140	$ 1,917,176
Certificates Of Deposits And US Treasury Obligations [Member]
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	4,749,924	11,499,768
Money Market Funds [Member]
Cash and Cash Equivalents [Line Items]
Cash and Cash Equivalents	$ 543,586	$ 441,715

Note 2 - Summary of Significant Accounting Policies (Details) - Cash Restricted Under Security Agreements - USD ($)	Jul. 31, 2014	Apr. 30, 2014
Australian Renewable Energy Agency [Member]
Current:
Restricted Cash And Cash Equivalents, Current	$ 5,237,037	$ 5,179,960
NJBPU Agreement [Member]
Current:
Restricted Cash And Cash Equivalents, Current	100,000	100,000
Long Term:
Restricted Cash And Cash Equivalents, Noncurrent	125,000	225,000
Oregon Department of State Lands [Member]
Current:
Restricted Cash And Cash Equivalents, Current	1,200,000	845,000
Barclays Bank Agreement [Member]
Long Term:
Restricted Cash And Cash Equivalents, Noncurrent	$ 964,656	$ 996,696

Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Exchange Gain (Loss) - USD ($)	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Foreign Exchange Gain (Loss) [Abstract]
Foreign exchange (loss) gain	$ (5,658)	$ 21,770

Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Currency Denominated Certificates of Deposit and Cash Accounts - USD ($)	Jul. 31, 2014	Apr. 30, 2014
Restricted [Member]
Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Currency Denominated Certificates of Deposit and Cash Accounts [Line Items]
Foreign currency denominated certificates of deposit and cash accounts	$ 6,201,693	$ 6,176,656
Unrestricted [Member]
Note 2 - Summary of Significant Accounting Policies (Details) - Foreign Currency Denominated Certificates of Deposit and Cash Accounts [Line Items]
Foreign currency denominated certificates of deposit and cash accounts	423,175	1,232,111
Foreign currency denominated certificates of deposit and cash accounts	$ 6,624,868	$ 7,408,767

Note 2 - Summary of Significant Accounting Policies (Details) - Revenues by Major Customers	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
European Union (WaverPort Project) [Member]
Revenue, Major Customer [Line Items]
Revenue	62.00%	35.00%
Mitsui Engineering And Ship Building [Member]
Revenue, Major Customer [Line Items]
Revenue	31.00%
US Department of Energy [Member]
Revenue, Major Customer [Line Items]
Revenue	7.00%	26.00%
UK Government's Technology Strategy Board [Member]
Revenue, Major Customer [Line Items]
Revenue		38.00%
Revenue	100.00%	99.00%

Note 3 - Marketable Securities (Details) - Marketable Securities That Mature Within One Year - USD ($)	Jul. 31, 2014	Apr. 30, 2014
US Treasury obligations [Member]
Note 3 - Marketable Securities (Details) - Marketable Securities That Mature Within One Year [Line Items]
US Treasury obligations	$ 17,244,357	$ 14,493,881
US Treasury obligations	$ 17,244,357	$ 14,493,881

Note 4 - Balance Sheet Detail (Details) - Balance Sheet Detail - USD ($)	Jul. 31, 2014	Apr. 30, 2014
Accounts receivable, net
Accounts receivable		$ 308,731
		308,731
Patents
Patents	$ 1,536,029	1,536,029
Accumulated amortization	(914,805)	(707,731)
	621,224	828,298
Accrued expenses
Project costs	1,260,217	1,263,293
Contract loss reserve	254,186
Employee incentive payments	490,118	310,370
Accrued salary and benefits	476,297	455,909
Legal and accounting fees	938,195	168,402
Goods and services tax (GST) due to Australian Tax Office		470,905
Other	320,210	262,360
	$ 3,739,223	$ 2,931,239

Note 5 - Related Party Transactions (Details) - USD ($)	1 Months Ended	3 Months Ended
Note 5 - Related Party Transactions (Details) - USD ($)	Apr. 30, 2014	Jul. 31, 2014
Former Executive Vice Chairman [Member] \| Consulting Fees [Member]
Note 5 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party		$ 60,000
Former Executive Vice Chairman [Member]
Note 5 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Term of Agreement	15 months
Related Party Transaction, Monthly Consulting Fee	$ 20,000
Interim Chief Executive Officer [Member] \| Consulting Fees [Member]
Note 5 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Expenses from Transactions with Related Party		53,813
Interim Chief Executive Officer [Member]
Note 5 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Daily Consulting Fee		$ 1,500

Note 5 - Related Party Transactions (Details) - Related Party Transactions	3 Months Ended
	Jul. 31, 2014 USD ($)
Related Party Transactions [Abstract]
Related party consulting expense	$ 113,813

Note 6 - Debt (Details) - USD ($)	1 Months Ended
Note 6 - Debt (Details) - USD ($)	Nov. 30, 2011	Jul. 31, 2014	Apr. 30, 2014
New Jersey Board of Public Utilities [Member]
Note 6 - Debt (Details) [Line Items]
Long-term Debt	$ 500,000
Long Term Debt Payment Terms	5 years
Long-term Debt		$ 225,000	$ 250,000

Note 6 - Debt (Details) - Long-term Debt - USD ($)	Jul. 31, 2014	Apr. 30, 2014
Long-term Debt, Unclassified [Abstract]
Total debt	$ 225,000	$ 250,000
Current portion of long-term debt	(100,000)	(100,000)
Long-term debt	$ 125,000	$ 150,000

Note 7 - Deferred Credits Payable (Details)	Jul. 31, 2014 USD ($)	Apr. 30, 2014 USD ($)	Apr. 30, 2001 USD ($) T
Customer Advances And Deposits Disclosure [Text Block] [Abstract]
Customer Advances and Deposits			$ 600,000
Deferred Credits Payable Option Details \| T			500,000
Deferred Credits Payable Market Discount Rate			30.00%
Deferred Credits Payable Market Liquidated Damages Rate			30.00%
Customer Advances or Deposits, Noncurrent	$ 600,000	$ 600,000

Note 8 - Stock-Based Compensation (Details) - USD ($)	3 Months Ended
Note 8 - Stock-Based Compensation (Details) - USD ($)	Jul. 31, 2014	Jul. 31, 2013	Apr. 29, 2014
Employee Stock Option [Member]
Note 8 - Stock-Based Compensation (Details) [Line Items]
Allocated Share-based Compensation Expense	$ 1,000	$ 220,000
Restricted Stock [Member] \| Including Non-employee Compensation [Member]
Note 8 - Stock-Based Compensation (Details) [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	1 year 328 days
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized	$ 63,000
Restricted Stock [Member] \| Performance-based vesting [Member]
Note 8 - Stock-Based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Forfeitures (in Shares)	9,380
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number (in Shares)	37,329
Restricted Stock [Member]
Note 8 - Stock-Based Compensation (Details) [Line Items]
Allocated Share-based Compensation Expense	$ 12,000	10,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)	0
Expected to Vest [Member]
Note 8 - Stock-Based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number (in Shares)	328,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	8 years 255 days
Including Non-employee Compensation [Member]
Note 8 - Stock-Based Compensation (Details) [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options	$ 235,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	2 years 6 months
Performance-based vesting [Member]
Note 8 - Stock-Based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	115,786
Share-based Compensation Arrangement by Share-based Payment Award, Shares Issued in Period (in Shares)	0
Allocated Share-based Compensation Expense	$ 13,000	$ 230,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)		$ 1.12
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term	4 years 146 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in Shares)	0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	1,010,041		1,472,292
Treasury Stock, Shares, Acquired (in Shares)	806	4,081

Note 8 - Stock-Based Compensation (Details) - Weighted Average Fair Value Assumptions for Stock-Based Compensation	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013
Weighted Average Fair Value Assumptions for Stock-Based Compensation [Abstract]
Risk-free interest rate		1.60%
Expected dividend yield		0.00%
Expected life (in years)		6 years 109 days
Expected volatility		74.61%

Note 8 - Stock-Based Compensation (Details) - Stock Options Under the Plans - $ / shares		3 Months Ended
	Apr. 30, 2014	Jul. 31, 2014
Stock Options Under the Plans [Abstract]
Shares Under Options	1,472,292
Weighted Average Exercise Price	$ 5.53
Weighted Average Remaining Contractual Term	5 years 328 days	5 years 292 days
Exercisable as of July 31, 2014		676,838
Exercisable as of July 31, 2014		$ 6.32
Exercisable as of July 31, 2014		4 years 146 days
Forfeited		(462,251)
Forfeited		$ 7.21
Shares Under Options		1,010,041
Weighted Average Exercise Price		$ 4.77

Note 8 - Stock-Based Compensation (Details) - Non-Vested Restricted Stock Under the Plans - Non-vested Restricted Stock [Member]	3 Months Ended
	Jul. 31, 2014 $ / shares shares
Note 8 - Stock-Based Compensation (Details) - Non-Vested Restricted Stock Under the Plans [Line Items]
Number of Shares \| shares	2.23
Weighted Average Price Per Share \| $ / shares	$ 97,610
Forfeited \| shares	2.30
Forfeited \| $ / shares	$ (9,380)
Vested \| shares	2.36
Vested \| $ / shares	$ (10,622)
Number of Shares \| shares	2.21
Weighted Average Price Per Share \| $ / shares	$ 77,608

Note 9 - Commitments and Contingencies (Details)	15 Months Ended
Note 9 - Commitments and Contingencies (Details)	Jul. 31, 2014 USD ($)	Jul. 31, 2014 EUR (€)
Spanish Tax Authorities [Member]
Note 9 - Commitments and Contingencies (Details) [Line Items]
Input Tax	$ 250,000
Securities Class Actions [Member]
Note 9 - Commitments and Contingencies (Details) [Line Items]
Loss Contingency, Pending Claims, Number	4	4
Letters of Credit Outstanding, Amount	$ 373,574	€ 278,828

Note 10 - Income Taxes (Details) - USD ($)	3 Months Ended
Note 10 - Income Taxes (Details) - USD ($)	Jul. 31, 2014	Jul. 31, 2013
Income Tax Disclosure [Abstract]
Income Tax Expense (Benefit)	$ 0	$ 0

Note 11 - Operating Segments and Geographic Information (Details)	3 Months Ended
	Jul. 31, 2014
UNITED STATES
Note 11 - Operating Segments and Geographic Information (Details) [Line Items]
Number of Reportable Segments	1
UNITED KINGDOM
Note 11 - Operating Segments and Geographic Information (Details) [Line Items]
Number of Reportable Segments	1
AUSTRALIA
Note 11 - Operating Segments and Geographic Information (Details) [Line Items]
Number of Reportable Segments	1
Number of Operating Segments	1

Note 11 - Operating Segments and Geographic Information (Details) - Geographic Segment Information - USD ($)	3 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Apr. 30, 2014
North America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers	$ 1,540,528	$ 287,752
Operating loss	(2,582,613)	(3,122,599)
July 31, 2014
Long-lived assets	275,993		$ 305,314
Total assets	28,718,561		31,313,240
Europe [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues from external customers		173,175
Operating loss	(392,868)	(315,402)
July 31, 2014
Long-lived assets	9,457		12,024
Total assets	769,569		1,003,205
Asia and Australia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Operating loss	(494,072)	(380,152)
July 31, 2014
Long-lived assets			175
Total assets	5,731,395		5,768,390
Revenues from external customers	1,540,528	460,927
Operating loss	(3,469,553)	$ (3,818,153)
Long-lived assets	285,450		317,513
Total assets	$ 35,219,525		$ 38,084,835

Note 12 - Subsequent Event (Details)	Jul. 31, 2014 USD ($)	Jul. 31, 2014 AUD ($)	Mar. 31, 2014 USD ($)	Mar. 31, 2014 AUD ($)
Grant Funding [Member]
Note 12 - Subsequent Event (Details) [Line Items]
Restricted Cash and Cash Equivalents	$ 5,237,037	$ 5,595,723	$ 5,200,000	$ 5,600,000

Label	Element	Value
Proposed Cost of Building	optt_ProposedCostOfBuilding	$ 232,000,000
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares)	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1,087,649
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares)	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	1,290,274
Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners	us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners	11.80%
Subsequent Event [Member]
Interest Paid	us-gaap_InterestPaid	$ 109,051
Interest Paid	us-gaap_InterestPaid	$ 102,061
New Jersey Boardof Public Utilities [Member]
Restricted Cash and Cash Equivalents	us-gaap_RestrictedCashAndCashEquivalents	$ 500,000
Barclays Bank [Member]
Line of Credit Facility, Commitment Fee Percentage	us-gaap_LineOfCreditFacilityCommitmentFeePercentage	1.00%
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	$ 800,000
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	$ 964,656
Long-term Line of Credit	us-gaap_LineOfCredit	$ 278,892
Long-term Line of Credit	us-gaap_LineOfCredit	$ 373,660
Victorian Wave Partners Pty Ltd [Member]
Potential Grant Revenue	optt_PotentialGrantRevenue	$ 66,500,000
Potential Grant Revenue	optt_PotentialGrantRevenue	$ 62,000,000
Foreign Tax Authority [Member] \| Australian Taxation Office [Member]
Goods and services tax (GST) due to Australian Tax Office	optt_GoodsAndServicesTaxDueToForeignOffice	$ 508,702
Goods and services tax (GST) due to Australian Tax Office	optt_GoodsAndServicesTaxDueToForeignOffice	$ 476,094
Three Letters Of Credit [Member] \| Oregon Departmentof State Lands [Member]
Line of Credit Facility, Maximum Borrowing Capacity	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity	$ 1,200,000
Victorian Wave Partners Pty Ltd [Member] \| OPTA [Member]
Ownership Percentage	optt_OwnershipPercentage	100.00%
Ownership Percentage	optt_OwnershipPercentage	100.00%
Intangible Assets, Amortization Period [Member] \| Revised Estimate [Member]
Finite-Lived Intangible Asset, Useful Life	us-gaap_FiniteLivedIntangibleAssetUsefulLife	1 year
Intangible Assets, Amortization Period [Member] \| Prior To Impairment Review [Member]
Finite-Lived Intangible Asset, Useful Life	us-gaap_FiniteLivedIntangibleAssetUsefulLife	5 years