July 19 (Reuters) - Exxon Mobil Corp said on Monday it appointed former United Airlines and Xerox executive Kathryn Mikells as chief financial officer, effective Aug. 9.

Andrew Swiger, Exxon's principal financial officer and senior vice president, will retire on Sept.1 after more than 43 years of service.

(Reporting by Arunima Kumar in Bengaluru; Editing by Shinjini Ganguli)