SECURITIES AND EXCHANGE COMMISSIONWashington, D.C. 20549

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FORM 40-F/A

|o                                           | REGISTRATION STATEMENT PURSUANT TO SECTION 12(B) OR (G) OF THE SECURITIES EXCHANGE ACT OF 1934
|------------------------------------------- | ----------------------------------------------------------------------------------------------
|OR                                         
|ý                                           | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(D) OF THE SECURITIES EXCHANGE ACT OF 1934          
|FOR THE FISCAL YEAR ENDED DECEMBER 31, 2004
|COMMISSION FILE NUMBER 000-31815           

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HYDROGENICS CORPORATION(Exact name of Registrant as specified in its charter)

Canada(Province or other jurisdiction of incorporation or organization)

3629(Primary Standard Industrial Classification Code Number (if applicable))

Not applicable(I.R.S. Employer Identification Number (if applicable))

5985 McLaughlin Road, Mississauga, Ontario, Canada L5R 1B8, (905) 361-3660(Address and telephone number of Registrant's principal executive offices)

CT Corporation System, 111 Eighth Avenue, New York, New York 10011, (212) 894-8400(Name, address (including zip code) and telephone number (including area
code) of agent for service in the United States)

Securities
registered or to be registered pursuant to Section 12(b) of the Act:None.

Securities
registered or to be registered pursuant to Section 12(g) of the Act: Common shares

Securities
for which there is a reporting obligation pursuant to Section 15(d) of the Act:None.

For
annual reports, indicate by check mark the information filed with this Form

ý

Annual information form

ý

Audited annual financial information


Indicate
the number of outstanding shares of each of the issuer's classes of capital or common stock as of the close of the period covered by the annual report

At December 31, 2004, 64,626,989 common shares were issued and outstanding

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Indicate
by check mark whether the Registrant by filing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to
Rule 12g3-2(b) under the Securities Exchange Act of 1934 (the "Exchange Act"). If "Yes" is marked, indicate the file number assigned to the Registrant in connection with such Rule.

Yes o    No ý

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act
of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the
past 90 days.

Yes ý    No o



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EXEMPTION FROM NASDAQ REQUIREMENT

The Company entered into a share exchange offer (the "Take-over Bid") for all of the issued and outstanding shares of Stuart Energy Systems Corporation ("Stuart
Energy"), a widely-held Canadian corporation listed on the Toronto Stock Exchange ("TSX"). By a letter from NASDAQ dated December 10, 2004, the Company was granted an exemption from the
shareholder approval requirements of Marketplace Rule 4350(i)(1)(C) with respect to the Take-over Bid. The home country practice followed by the Company in lieu of such requirement was to not
obtain shareholder approval of the Take-over Bid as such approval is not required by Canadian or Ontario law and is contrary to generally accepted business practices for widely-held companies listed
on the TSX.

UNDERTAKING

The registrant undertakes to make available, in person or by telephone, representatives to respond to inquiries made by the Commission staff, and to furnish
promptly, when requested to do so by the Commission staff, information relating to: the securities registered pursuant to Form 40-F/A; the securities in relation to which the
obligation to file an annual report on Form 40-F/A arises; or transactions in said securities.

CONSENT TO SERVICE OF PROCESS

The Company has previously filed a Form F-X in connection with the class of securities in relation to which the obligation to file this report
arises.

Any
change to the name or address of the agent for service of process of the registrant shall be communicated promptly to the Securities and Exchange Commission by an amendment to the
Form F-X referencing the file number of the registrant.

2

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant hereby certifies that it meets all of the requirements for filing on
Form 40-F/A and that it has duly caused and authorized the undersigned to sign this annual report on its behalf.

|                  |  | HYDROGENICS CORPORATION
|----------------- |  | -----------------------
|                  |  |                        
|                  |  | By:                    
|                  |  |                        
|Date: May 3, 2005 |  |                        

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EXHIBITS

|Exhibit |  | Description                                                                                                          
|------- |  | ---------------------------------------------------------------------------------------------------------------------
|99.1    |  | Certification of Chief Executive Officer of the Registrant pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.
|99.2    |  | Certification of Chief Financial Officer of the Registrant pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.

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