---

---

U.S. Securities and Exchange CommissionWashington, D.C. 20549

Form 40-F/A

|o  | Registration statement pursuant to section 12 of the Securities Exchange Act of 1934   
|-- | ---------------------------------------------------------------------------------------
|or
|ý  | Annual report pursuant to section 13(a) or 15(d) of the Securities Exchange Act of 1934

|For the fiscal year ended December 31, 2002 | Commission File Number 0-25270
|------------------------------------------- | ------------------------------

Ballard Power Systems Inc.(Exact name of Registrant as specified in its charter)

|CANADA(Province or other jurisdiction of incorporation or organization) |  | 3261(Primary Standard Industrial Classification Code Number (if applicable)) |  | Not applicable(I.R.S. Employer Identification Number (if applicable))
|----------------------------------------------------------------------- |  | ---------------------------------------------------------------------------- |  | ---------------------------------------------------------------------

4343 North Fraser Way
Burnaby, British Columbia V5J 5J9
(604) 454-0900(Address and telephone number of Registrant's principal executive offices)

Corporation Trust Company
1633 Broadway
New York, New York 10019
(212) 894-8940Address (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.

|Title of each class |  | Name of each exchange on which registered
|------------------- |  | -----------------------------------------
|Not applicable      |  | Not Applicable                           

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. Non-Applicable

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

|ý    Annual information form |  | o    Audited annual financial statements
|---------------------------- |  | ----------------------------------------

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.

115,789,374 Common Shares

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 filing number assigned to the Registrant in connection
with such Rule.

|Yes    o |  | 82- |  | 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 Exchange Act 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
|-------- |  |  |  | -------

---

---

---

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; the securities in relation to which the
obligation to file an annual report on Form 40-F arises; or transactions in said securities.

---

SIGNATURES

Signatures
Pursuant to the requirements of the Exchange Act, the Registrant certifies that it meets all of the requirements for filing on Form 40-F and has duly caused this
annual report to be signed on its behalf by the undersigned, thereto duly authorized.

Registrant:
Ballard Power Systems Inc.

|By (Signature and Title) |  | /s/NOORDIN S. K. NANJINoordin S. K. Nanji
Vice President, Corporate Strategy & Development and Corporate Secretary
|------------------------ |  | ------------------------------------------------------------------------------------------------------------------

Date:
April 30, 2003

---

EXHIBIT LIST

|Exhibit |  | Description                                                                       
|------- |  | ----------------------------------------------------------------------------------
|99.1    |  | Annual Information Form for Ballard Power Systems Inc., dated as of April 30, 2003
|99.2    |  | Certification pursuant to Section 302 of the Sarbanes-Oxley Act of 2002           
|99.3    |  | Certification pursuant to Section 906 of the Sarbanes-Oxley Act of 2002           

---

QuickLinks