EXHIBIT 5.2

March 5, 2013

FirstEnergy Corp.

76 South Main Street

Akron, Ohio 44308

Ladies and Gentlemen:

We have acted as special counsel to FirstEnergy Corp., an Ohio corporation (the “Company”), in connection with the registration, pursuant to a Registration Statement on Form S-3, as amended (File No. 333-181519) (the “Registration Statement”), filed with the Securities and Exchange Commission (the “Commission”) under the Securities Act of 1933, as amended (the “Act”), of the offering and sale by the Company of $650,000,000 aggregate principal amount of its 2.75% Notes, Series A, due 2018 and $850,000,000 aggregate principal amount of its 4.25% Notes, Series B, due 2023 (collectively, the “Notes”), issued under an Indenture, dated as of November 15, 2001, as amended (the “Senior Note Indenture”), by and between the Company and The Bank of New York Mellon Trust Company, N.A., as successor trustee (the “Trustee”), as supplemented by an Officer’s Certificate, dated March 5, 2013 (the “Officer’s Certificate,” and together with the Senior Note Indenture, hereinafter referred to as the “Indenture”) and sold pursuant to the Underwriting Agreement, dated February 28, 2013, by and among J.P. Morgan Securities LLC, Morgan Stanley & Co. LLC, RBS Securities Inc., Citigroup Global Markets Inc., Goldman, Sachs & Co., PNC Capital Markets LLC, RBC Capital Markets, LLC and Scotia Capital (USA) Inc., as Representatives of the Underwriters listed on Schedule I thereto (collectively, the “Underwriters”) and the Company (the “Underwriting Agreement”). This opinion is being furnished in accordance with the requirements of Item 601(b)(5) of Regulation S-K under the Act.

We have examined originals or certified copies of such corporate records of the Company and other certificates and documents of officials of the Company, public officials and others as we have deemed appropriate for purposes of this letter. We have also assumed (i) the genuineness of all signatures, the legal capacity of all natural persons, the authenticity of all documents submitted to us as originals, the conformity to authentic original documents of all copies submitted to us as conformed and certified or reproduced copies, (ii) that the Notes

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March 5, 2013

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conform to the specimens thereof we have reviewed, and (iii) that the Indenture and the Notes have been duly authorized, executed, and delivered by or on behalf of the Company. We have also assumed that the Indenture is a valid and binding obligation of the Trustee, enforceable against the Trustee in accordance with its terms. As to various questions of fact relevant to this letter, we have relied, without independent investigation, upon certificates of public officials and certificates of officers of the Company, all of which we assume to be true, correct and complete.

Based upon the foregoing and subject to the assumptions, exceptions, qualifications and limitations set forth herein, we are of the opinion that when the Notes have been duly executed by the Company, duly authenticated by the Trustee in accordance with the terms of the Indenture, and delivered to and paid for by the Underwriters pursuant to the terms of the Underwriting Agreement, the Notes will be valid and binding obligations of the Company.

The opinions and other matters in this letter are qualified in their entirety and subject to the following:

FirstEnergy Corp.

March 5, 2013

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We hereby consent to the filing of this opinion as an exhibit to a Current Report on Form 8-K filed by the Company with the Commission on or about the date hereof, to the incorporation by reference of this opinion into the Registration Statement and to the use of our name in the Prospectus dated May 18, 2012 and the Prospectus Supplement dated February 28, 2013, forming a part of the Registration Statement under the caption “Legal Matters.” In giving this consent, we do not thereby admit that we are within the category of persons whose consent is required under Section 7 of the Act and the rules and regulations thereunder.