EXHIBIT 32.1

                    CERTIFICATION OF CHIEF EXECUTIVE OFFICER

      Pursuant to 18 U.S.C. Section 1350, as created by Section 906 of the
Sarbanes-Oxley Act of 2002, the undersigned officer of IDEX Corporation (the
"Company") hereby certifies, to such officer's knowledge, that:

      (i) the accompanying Quarterly Report on Form 10-Q of the Company for the
      quarterly period ended September 30, 2004 (the "Report") fully complies
      with the requirements of Section 13(a) or Section 15(d), as applicable, of
      the Securities Exchange Act of 1934, as amended; and

      (ii) the information contained in the Report fairly presents, in all
      material respects, the financial condition and results of operations of
      the Company.

November 3, 2004                 /s/ Dennis K. Williams
                                 ------------------------------------
                                 Dennis K. Williams
                                 Chairman, President and Chief Executive Officer