Registration No. 333-124781

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

POST-EFFECTIVE

AMENDMENT NO. 1

TO

Form F-10

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Domtar Inc.

(Exact name of registrant as specified in its charter)

395 de Maisonneuve Blvd. West

Montreal, Quebec, Canada H3A 1L6

(514) 848-5400

(Address and telephone number of Registrant’s principal executive offices)

CT Corporation System

111 Eighth Avenue

New York, New York 10011

(212) 894-8690

(Name, address (including zip code) and telephone number (including area code) of agent for service in the United States)

Copies of all communications to:

     Approximate date of commencement of proposed sale to the public: As soon as practicable after this Registration Statement becomes effective.

Province of Quebec, Canada

(Principal jurisdiction regulating this offering)

     It is proposed that this filing shall become effective (check appropriate box):

     If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to the home jurisdiction’s shelf prospectus offering procedures, check the following box.    þ

     The registrant hereby amends this Registration Statement on such date or dates as may be necessary to delay its effective date until the Registration Statement shall become effective as provided in Rule 467 under the Securities Act of 1933 or on such date as the Commission, acting pursuant to Section 8(a) of the Act, may determine.

EXPLANATORY NOTE

      The sole purpose of this post-effective Amendment No. 1 is to file the calculation of earnings coverage ratios as an exhibit to the Registration Statement. Accordingly, this Amendment consists only of the facing page, this explanatory note and Parts II and III of the Registration Statement.

PART II

INFORMATION NOT REQUIRED TO BE DELIVERED

TO OFFEREES OR PURCHASERS

Indemnification of Directors and Officers

      Under Section 124 of the Canada Business Corporations Act, the Registrant may indemnify a present or former director or officer or a person who acts or acted at the Registrant’s request as a director or officer of another corporation of which such Registrant is or was a shareholder or creditor, and his heirs and legal representatives, against all costs, charges and expenses, including an amount paid to settle an action or satisfy a judgment, reasonably incurred by him in respect of any civil, criminal or administrative action or proceeding to which he is made a party by reason of his position with the Registrant or such other corporation, as the case may be, provided that such person acted honestly and in good faith with a view to the best interests of the Registrant and, in the case of a criminal or administrative action or proceeding that is enforced by a monetary penalty, such person had reasonable grounds for believing that his conduct was lawful. Such indemnification may be made in connection with an action by or on behalf of the Registrant or such other corporation, as the case may be, only with court approval. A director or officer referred to above is entitled to such indemnification from the Registrant as a matter of right if he or she was substantially successful on the merits and fulfilled the conditions set forth above.

      In accordance with the Canada Business Corporations Act, the by-laws of the Registrant indemnify a director or officer, a former director or officer, a person who acts or acted at the Registrant’s request as a director or officer of a body corporate of which the Registrant is or was a shareholder or creditor (or a person who undertakes or had undertaken any liability on behalf of the Registrant or any such body corporate), or such person’s heirs and legal representatives, against all costs, charges and expenses, including an amount paid to settle an action or satisfy a judgment, reasonably incurred by such person in respect of any civil, criminal or administrative action or proceeding to which such person is made a party by reason of being or having been a director or officer of the Registrant or a director, officer or other similar executive of such other corporation or other organization, to the fullest extent permitted by law, if: (a) the person acted honestly and in good faith with a view to the best interests of the Registrant and (b) in the case of criminal or administrative action or proceeding that is enforced by a monetary penalty, the person had reasonable grounds for believing that their conduct was lawful. The Registrant is authorized to enter into agreements evidencing its indemnity in favour of the foregoing persons to the full extent permitted by law and may purchase and maintain insurance against the risk of its liability to indemnify pursuant to the foregoing provisions.

      The Registrant participates in the purchase of directors’ and officers’ liability insurance, which, subject to the provisions contained in the policy, protects the directors and officers against all claims made during each year of the applicable policy period (currently January, 2005 to January, 2006). This policy does not provide coverage for losses arising from the breach of fiduciary responsibilities under statutory or common law or from the violation or enforcement of pollutant laws and regulations.

      Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers or persons controlling the Registrant pursuant to the foregoing provisions, the Registrant has been informed that in the opinion of the U.S. Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act and is therefore unenforceable.

Exhibits

      The following exhibits have been filed as part of this Registration Statement on Form F-10:

PART III

UNDERTAKING AND CONSENT TO SERVICE OF PROCESS

      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 this post-effective Amendment No. 1 to Form F-10 or to transactions in such securities.

      The Registrant has previously filed with the Commission a written irrevocable consent and power of attorney on Form F-X.

      Any change to the name or address of the agent for service of the Registrant shall be communicated promptly to the Commission by amendment to Form F-X referencing the file number of this Registration Statement.

SIGNATURES

      Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form F-10 and has duly caused this post-effective Amendment No. 1 to the Registration Statement (File No. 333-124781) to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Montreal, Province of Quebec, Canada, on June 20, 2005.

      Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed below by the following persons on the 20th day of June, 2005.

Index to Exhibits

      The following exhibits have been filed as part of this Registration Statement on Form F-10: