EXHIBIT 5.1

                              [Exxon Letterhead]



                                                       September 28, 1999


Securities and Exchange Commission
450 Fifth Street, N. W.
Washington, D. C.  20549

Ladies and Gentlemen:

     As Counsel for Exxon Corporation, a New Jersey corporation ("Exxon"), I
am familiar with its Restated Certificate of Incorporation and By-laws, as
amended to date. I have examined its corporate proceedings in connection with
the preparation and filing under the Securities Act of 1933, as amended (the
"Securities Act"), of a registration statement on Form S-8 (the "Registration
Statement"), covering shares (the "Exxon Plan Shares") of Exxon's common
stock, no par value, (i) to be issued in connection with outstanding awards
granted under the 1995 Mobil Incentive Compensation and Stock Ownership Plan,
1991 Mobil Incentive Compensation and Stock Option Plan and 1986 Mobil
Incentive Compensation and Stock Option Plan (collectively, the "Incentive
Plans"), which awards are being assumed by Exxon pursuant to Section 1.04 of
the Agreement and Plan of Merger dated as of December 1, 1998 among Exxon,
Mobil Corporation, and Lion Acquisition Subsidiary Corporation (the "Merger
Agreement"), and (ii) available for issuance under the Employees Savings Plan
of Mobil Oil Corporation (the "Savings Plan") (the Incentive Plans and the
Savings Plan being herein collectively referred to as the "Plans").

     I have also examined originals or copies, certified or otherwise
authenticated to my satisfaction, of all such documents and records and
conducted such other investigations of fact and law as I have deemed necessary
as a basis for this opinion. As to certain questions of fact, I have relied
upon statements of officers of Exxon and others.

     In rendering this opinion I have assumed that prior to the issuance of
any of the Exxon Plan Shares (i) the Registration Statement, as then amended,
will have become effective under the Securities Act and (ii) the transactions
contemplated by the Merger Agreement are consummated in accordance with the
terms thereof.

     On the basis of the foregoing, I am of the opinion that the Exxon Plan
Shares, when issued and delivered in accordance with the terms and conditions
of the Plans, will be duly authorized, validly issued, fully paid, and
non-assessable.

     This opinion relates solely to the federal laws of the United States and
the corporate law of the State of New Jersey. I hereby consent to the filing
of this opinion as an exhibit to the Registration Statement.

                                                         Very truly yours,



                                                         /s/ James E. Parsons