Diane Wood

Associate General Counsel and Corporate Secretary

Pinnacle West Capital Corporation

P.O. Box 53999

Phoenix, Arizona 85072-3999

October 17, 2013

VIA EDGAR AND E-MAIL

Ms. Mara L. Ransom

Assistant Director

Division of Corporation Finance

U.S. Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549-7010

Re: Pinnacle West Capital Corporation Form 10-K for the Fiscal Year Ended December 31, 2012 Filed February 22, 2013 Definitive Proxy Statement on Schedule 14A Filed March 28, 2013 Response dated September 20, 2013 File No. 001-08962

Dear Ms. Ransom:

Reference is made to the comment letter (the “Comment Letter”) dated October 8, 2013 from the staff of the Division of Corporation Finance of the Securities and Exchange Commission with respect to the above-captioned filings of Pinnacle West Capital Corporation (the “Company”).  As we discussed on October 11, 2013, the Company will need additional time to respond to the Comment Letter and will submit its response by October 28, 2013.

Very truly yours,

/s/ Diane Wood

Diane Wood

Associate General Counsel and Corporate Secretary