Exhibit F-1
                                                                     -----------


                                                     April 2, 2001


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

            Re:   FirstEnergy Corp.
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Ladies and Gentlemen:

            We have examined the  Declaration  on Form U-1, dated April 2, 2002,
under the Public  Utility  Holding  Company Act of 1935, as amended (the "Act"),
filed by  FirstEnergy  Corp.  ("FirstEnergy"),  of which this opinion is to be a
part. (The Declaration is hereinafter referred to as the "Declaration.")

            The Declaration  contemplates,  among other things, the solicitation
by FirstEnergy of proxies (the  "Solicitation")  from its  shareholders  seeking
approval of the issuance of additional shares of FirstEnergy  common stock under
the FirstEnergy Corp.  Executive and Director  Incentive  Compensation Plan (the
"Plan").

            We have examined  copies,  signed,  certified or otherwise proven to
our  satisfaction,   of  the  charter  documents  and  Code  of  Regulations  of
FirstEnergy.  We have  also  examined  such  other  documents,  instruments  and
agreements,  including the Plan, and have made such further  investigation as we
have deemed necessary as a basis for this opinion.

            We are  members of the bars of the States of New Jersey and New York
and are not expert in the laws of any  jurisdiction  other than the laws of such
states and the federal laws of the United  States of America.  As to all matters
herein which are governed by the laws of the State of Ohio and the  Commonwealth
of  Pennsylvania,  we have relied upon the opinion of Michael R. Beiting,  Esq.,
which is being filed as Exhibit F-2 to the Declaration.

            Based  upon and  subject to the  foregoing,  and  assuming  that the
Solicitation  is carried out in accordance with the  Declaration,  we are of the
opinion that:

                  (a)   all State laws  applicable  to the  Solicitation
            will have been complied with;

                  (b)   FirstEnergy is validly organized and existing
            in the State of Ohio;

                  (c)   the  Solicitation will not violate the legal rights
            of the holders of any securities issued by FirstEnergy, or
            any "associate company" thereof, as defined in the Act.

            We hereby consent to the filing of this opinion as an exhibit to the
Declaration  and in any  proceedings  before the Commission  that may be held in
connection therewith.


                                    Very truly yours,


                                    /s/ THELEN REID & PRIEST LLP
                                    Thelen Reid & Priest LLP