                                                                     Exhibit 5.1

                                December 17, 2002

Pinnacle West Capital Corporation
400 North Fifth Street
Phoenix, Arizona 85004

     Re:  Registration Statement on Form S-3

Ladies and Gentlemen:

     We have acted as counsel to Pinnacle West Capital  Corporation,  an Arizona
corporation  (the  "Company"),   in  connection  with  the  preparation  of  the
registration statement on Form S-3, No. 333-101457 filed with the Securities and
Exchange  Commission (the  "Commission") by the Company on November 25, 2002 and
declared  effective by the  Commission on December 5, 2002 and the  registration
statement on Form S-3, No. 333-52476 filed with the Commission by the Company on
December 21, 2000 and declared  effective by the  Commission on January 11, 2001
(collectively,  the  "Registration  Statements").  The  Registration  Statements
relate to the issuance  and sale from time to time,  pursuant to Rule 415 of the
General Rules and Regulations (the "Rules") promulgated under the Securities Act
of 1933, as amended (the  "Securities  Act"),  of common stock, no par value, of
the Company ("Common  Stock") and other  securities,  with an aggregate  initial
public  offering price of up to  $600,000,000.  We have also acted as counsel to
the Company in  connection  with the offering and sale of 5,700,000  shares (the
"Firm Shares"),  pursuant to the Underwriting  Agreement dated December 17, 2002
(the  "Underwriting  Agreement")  between the Company and the underwriters named
therein (the  "Underwriters"),  and, at the election of the Underwriters,  up to
855,000  additional  shares (the  "Optional  Shares" and together  with the Firm
Shares, the "Offered Shares").

     This opinion is  delivered  in  accordance  with the  requirements  of Item
601(b)(5) of Regulation S-K under the  Securities  Act. We have examined (i) the
Registration Statements; (ii) the definitive prospectus, dated December 5, 2002,
and  the  prospectus   supplement  dated  December  17,  2002  (the  "Prospectus
Supplement")  (such  prospectus,   Prospectus   Supplement,   and  all  material
incorporated   therein  by  reference  being  hereinafter  referred  to  as  the
"Prospectus"),  relating to the Offered  Shares;  (iii) the Amended and Restated
Articles of  Incorporation  of the Company,  as  currently  in effect;  (iv) the
Bylaws of the Company as currently in effect; (v) the resolutions adopted by the
Board of Directors  of the Company and by the Special  Committee of the Board of
Directors of the Company relating to the filing of the  Registration  Statements
and the  offering  and sale of the  Offered  Shares;  and (vi) the  Underwriting
Agreement.  We have also  examined  originals or copies,  certified or otherwise
identified  to our  satisfaction,  of  such  records  of the  Company  and  such
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Pinnacle West Capital Corporation
December 17, 2002
Page 2

agreements,  certificates of public officials, certificates of officers or other
representatives   of  the  Company  and  others,   and  such  other   documents,
certificates  and records as we have deemed  necessary or appropriate as a basis
for the opinions set forth herein.

     Based  upon the  foregoing  and in  reliance  thereon,  and  subject to the
qualifications  and  limitations  set forth herein,  we are of the opinion that,
upon the  issuance  and delivery of the Offered  Shares in  accordance  with the
Underwriting  Agreement and receipt by the Company of the consideration therefor
set forth in the Prospectus,  and further  assuming that the Offered Shares have
been duly authenticated, executed, countersigned,  registered and delivered upon
payment  therefor,  the Offered Shares will be duly authorized,  validly issued,
fully paid and nonassessable.

     We do not express any opinion as to the laws of any jurisdiction other than
the laws of the State of Arizona  and the laws of the United  States of America.
This  opinion  is  limited  to the laws,  including  the  rules and  regulations
thereunder,  as in effect on the date  hereof.  We disclaim  any  obligation  to
advise you of any change in any of these sources of law or  subsequent  legal or
factual  developments  which  might  affect any  matters or  opinions  set forth
herein.

     We hereby  consent to the filing of this opinion with the  Commission as an
exhibit to the Registration Statement. In giving this consent, we do not thereby
admit that we are in the  category of persons  whose  consent is required  under
Section 7 of the Securities  Act or the rules and  regulations of the Commission
promulgated thereunder.

                                        Very truly yours,

                                        Snell & Wilmer LLP

                                        Snell & Wilmer LLP

