Exhibit 32.1

      CERTIFICATION OF CHIEF EXECUTIVE OFFICER AND CHIEF FINANCIAL OFFICER
                                   PURSUANT TO
                             18 U.S.C. SECTION 1350,
                             AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

      I, Tamer Husseini, certify, pursuant to 18 U.S.C. Section 1350, as adopted
pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the Quarterly
Report of Celeritek, Inc. on Form 10-Q for the quarterly period ended June 30,
2004 fully complies with the requirements of Section 13(a) or 15(d) of the
Securities Exchange Act of 1934 and that information contained in such Quarterly
Report fairly presents in all material respects the financial condition and
results of operations of Celeritek, Inc.

            By:    /s/  TAMER HUSSEINI
            ----------------------------------------
            Name:  Tamer Husseini
            Title: Chief Executive Officer

      I, Margaret E. Smith, certify, pursuant to 18 U.S.C. Section 1350, as
adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, that the
Quarterly Report of Celeritek, Inc. on Form 10-Q for the quarterly period ended
June 30, 2004 fully complies with the requirements of Section 13(a) or 15(d) of
the Securities Exchange Act of 1934 and that information contained in such
Quarterly Report fairly presents in all material respects the financial
condition and results of operations of Celeritek, Inc.

            By:   /s/  MARGARET E. SMITH
            ----------------------------------------
            Name: Margaret E. Smith
            Title: Chief Financial Officer