UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of report (date of earliest event reported): September 16, 2016

LENNOX INTERNATIONAL INC.

(Exact name of registrant as specified in its charter)

2140 Lake Park Blvd.

Richardson, Texas 75080

(Address of principal executive offices, including zip code)

Registrant’s telephone number, including area code:

(972) 497-5000

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

(d) Election of Director Max H. Mitchell.

On September 16, 2016, the Board elected Max H. Mitchell to the Board of Directors. Mr. Mitchell’s term will expire at the 2019 annual meeting of the stockholders of Lennox International Inc. (the “Company”).

Mr. Mitchell was also named to the Audit Committee and the Board Governance Committee.

As compensation for his service on the Board, Mr. Mitchell will receive an annual retainer of $100,000, at least $20,000 of which must be taken in the form of common stock of the Company, in accordance with the Company’s Board of Director compensation program. In addition, subject to continued service as a director, Mr. Mitchell will be eligible to receive a restricted stock unit (“RSU”) grant each year, with a targeted delivered value of $110,000. The RSUs under this program are scheduled to vest, subject to continued service as a director of the Company, three years following the grant date, and the other terms and conditions of the RSUs will be generally consistent with the Form of Restricted Stock Unit Award Agreement for Non-Employee Directors, filed as Exhibit 10.9 to the Company’s Annual Report on Form 10-K filed on February 15, 2013 and incorporated herein by reference. His compensation is consistent with the Company’s current Board compensation program applicable to the Company’s other outside directors.

The Board of Directors has affirmatively determined that Mr. Mitchell is independent and has no material direct or indirect interest in a related party transaction which requires disclosure.

Mr. Mitchell and the Company will enter into an indemnification agreement (the “Indemnification Agreement”) which will provide indemnification protection for Mr. Mitchell in connection with his service as a director of the Company. The agreement is substantially similar to the form filed as Exhibit 10.15 to the Company’s Registration Statement on Form S-1 (Registration No. 333-75725) filed on April 6, 1999 and incorporated herein by reference.

The Company issued a press release announcing Mr. Mitchell’s election on September 19, 2016, which is attached to this Form 8-K as Exhibit 99.1.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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