UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 20-F
                                 Amendment No. 1


|_|   REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR 12(g) OF THE
      SECURITIES EXCHANGE ACT OF 1934

                                       OR

|X|   ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
      ACT OF 1934

                                       OR

|_|   TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
      EXCHANGE ACT OF 1934


                        Commission file number: 000-30980

                               INFICON Holding AG
             (Exact name of Registrant as specified in its charter)

                              INFICON Holding Inc.
                 (Translation of Registrant's name into English)

                                   Switzerland
                 (Jurisdiction of incorporation or organization)

                                  INFICON Inc.
                              Two Technology Place
                          East Syracuse, New York 13057
                    (Address of principal executive offices)



Securities registered or to be registered pursuant to Section 12(b) of the Act.


                                      None

                               ------------------
<PAGE>

Securities registered or to be registered pursuant to Section 12(g) of the Act.


TITLE OF EACH CLASS:                            NAME OF EACH EXCHANGE ON WHICH
                                                REGISTERED:

INFICON Holding AG shares with a par value of     The SWX Swiss
CHF 10 each                                        Exchange

                               ------------------

Securities for which there is a reporting obligation pursuant to Section 15(d)
of the Act.

                               ------------------
                                      None

                                (Title of class)


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.

                                2,315,900 shares


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 |X| No |_| Not applicable.


Indicate by check mark which financial statement item the registrant has elected
to follow:

                             Item 17 |_| Item 18 |X|


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<PAGE>

                                EXPLANATORY NOTE

INFICON Holding AG (the "Company") hereby amends Items 15 and 19 of its Annual
Report on Form 20-F for the year ended December 31, 2004 filed with the
Securities and Exchange Commission on March 18, 2005. This Amendment does not
amend, update or restate any other items or sections of said Annual Report.

Item 15 is amended in its entirety to read as follows:

      Item 15. Controls and Procedures

      Conclusion Regarding the Effectiveness of Disclosure Controls and
      Procedures

      As of the end of the period covered by this report on Form 20-F, the
      Company carried out an evaluation of the effectiveness of the design and
      operation of its disclosure controls and procedures as defined in Rule
      13a-15(e) under the Securities Exchange Act of 1934. Based on the
      evaluation of these controls and procedures required by paragraph (b) of
      Rule 13a-15, the Company's Chief Executive Officer and Chief Financial
      Officer concluded that its disclosure controls and procedures are
      effective as of the end of the period covered by this annual report to
      provide reasonable assurance that information required to be disclosed in
      filings and submissions under the Exchange Act is recorded, processed,
      summarized, and reported within the time periods specified in the SEC's
      rules and forms.


      Changes in Internal Control over Financial Reporting

      There was no change in the Company's internal control over financial
      reporting (as defined in Rule 13a-15(f) under the Securities Exchange Act
      of 1934) that occurred during the year ended December 31, 2004 that has
      materially affected, or is reasonably likely to materially affect, the
      Company's internal control over financial reporting.


Item 19. Exhibits

Exhibits 31.1 and 31.2 are amended by adding the certifications of the Chief
Executive Officer and Chief Financial Officer, attached as Exhibits 31.1 and
31.2 hereto.


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<PAGE>

                                   SIGNATURES

The registrant hereby certifies that it meets all of the requirements for filing
on Form 20-F and that it has duly caused and authorized the undersigned to sign
this Amended Annual Report on Form 20-F on its behalf.


                                            INFICON Holding AG

Date: July 26, 2005                         /s/ Lukas Winkler
                                            ------------------------
                                            Name:  Lukas Winkler
                                            Title: President and Chief
                                                   Executive Officer


Date: July 26, 2005                         /s/ Peter G. Maier
                                            ------------------------
                                            Name:  Peter G. Maier
                                            Title: Vice-President and Chief
                                                   Financial Officer


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