EXHIBIT 99.1 KERR-McGEE CORPORATION Kerr-McGee Center Oklahoma City, Oklahoma 73125 CERTIFICATION OF CHAIRMAN REGARDING PERIODIC REPORT CONTAINING FINANCIAL STATEMENTS I, Robert M. Wohleber, the Chairman of the Benefits Committee of Kerr-McGee Corporation (the "Issuer"), in compliance with 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, hereby certify in connection with the Issuer's Annual Report on Form 11-K for the period that ended December 31, 2002 as filed with the Securities and Exchange Commission (the "Report") that: o the Report fully complies with the requirements of Sections 13(a) or 15(d) of the Securities Exchange Act of 1934; and o information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Issuer. /s/ Robert M. Wohleber - ---------------------- Robert M. Wohleber Chairman June 27, 2003 A signed original of this written statement required by Section 906 has been provided to Kerr-McGee Corporation and will be retained by Kerr-McGee Corporation and furnished to the Securities and Exchange Commission or its staff upon request. EXHIBIT 99.2 KERR-McGEE CORPORATION Kerr-McGee Center Oklahoma City, Oklahoma 73125 CERTIFICATION REGARDING PERIODIC REPORT CONTAINING FINANCIAL STATEMENTS I, Elizabeth T. Wilkinson, a member of the Benefits Committee of Kerr-McGee Corporation (the "Issuer"), in compliance with 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002, hereby certify in connection with the Issuer's Annual Report on Form 11-K for the period that ended December 31, 2002 as filed with the Securities and Exchange Commission (the "Report") that: o the Report fully complies with the requirements of Sections 13(a) or 15(d) of the Securities Exchange Act of 1934; and o information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Issuer. /s/ Elizabeth T. Wilkinson - -------------------------- Elizabeth T. Wilkinson June 27, 2003 A signed original of this written statement required by Section 906 has been provided to Kerr-McGee Corporation and will be retained by Kerr-McGee Corporation and furnished to the Securities and Exchange Commission or its staff upon request.