EXHIBIT 5.01

                    [PHILLIPS PETROLEUM COMPANY LETTERHEAD]

                                 March 6, 2001

Phillips Petroleum Company
Phillips Building
Bartlesville, Oklahoma 74004

Ladies and Gentlemen:

  I am Executive Vice President, General Counsel and Chief Administrative
Officer of, and have acted as counsel to, Phillips Petroleum Company, a
Delaware corporation ("Phillips" or the "Company"), and have represented the
Company in connection with the preparation and filing with the Securities and
Exchange Commission (the "Commission") under the Securities Act of 1933, as
amended (the "Act"), of a Registration Statement on Form S-4 (the "Registration
Statement"), relating to registration under the Act of up to 130,000,000 shares
of Common Stock, $1.25 par value per share, of Phillips (the "Common Stock").

  I have examined originals or copies, certified or otherwise identified to my
satisfaction, or such documents, corporate records, certificates of public
officials and other instruments as I have deemed necessary or advisable for the
purpose of rendering this opinion.

  Based on the foregoing, I am of the opinion that the shares of Common Stock
have been duly authorized and (i) when the Registration Statement has become
effective under the Act and (ii) when the shares of Common Stock have been duly
executed, countersigned and delivered by the Company upon the consummation of
the transaction as contemplated in the Registration Statement, such shares of
Common Stock will be validly issued, fully paid and nonassessable.

  I am a member of the Bar of the State of Oklahoma and my opinion is limited
to the Federal laws of the United States, the laws of the State of Oklahoma and
the Delaware General Corporation Law.

  I hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the use of my name under the heading "Legal
Matters" in the Prospectus forming a part of the Registration Statement.

                                          Very truly yours,

                                          /s/ J. Bryan Whitworth

                                          J. Bryan Whitworth
                                           Executive Vice President, General
                                           Counsel and Chief Administrative
                                           Officer

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