EXHIBIT 99.1

     CERTIFICATION PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002
                                (WILLIAM J. POST)

     I, William J. Post, the Chairman of the Board and Chief Executive Officer
of Arizona Public Service Company ("APS"), certify, to the best of my knowledge,
that: (a) the attached Quarterly Report on Form 10-Q of APS for the quarterly
period ended June 30, 2002 (the "June 2002 Form 10-Q") fully complies with the
requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934
and (b) the information contained in the June 2002 Form 10-Q Report fairly
presents, in all material respects, the financial condition and results of
operations of APS.


                                           William J. Post
                                           -------------------------------------
                                           William J. Post
                                           Chairman of the Board and Chief
                                           Executive Officer
                                           Date: August 13, 2002


The foregoing certificate is being furnished solely pursuant to Section 906 of
the Sarbanes-Oxley Act of 2002 (subsections (a) and (b) of Section 1350, Chapter
63, Title 18, United States Code) and is not being filed as part of the Form
10-Q or as a separate disclosure document.