By Sudarshan Varadhan and Anya George Tharakan

(Reuters) - Visa Inc <V.N> said Chief Executive Charles Scharf, who orchestrated the company's reunion with its European affiliate, is stepping down and will be succeeded by former American Express Co <AXP.N> President Alfred Kelly.

Kelly, who already sits on Visa's board of directors, will take over as CEO following Scharf's resignation, which is effective Dec. 1.

Kelly said in an interview with Reuters that he "got a front row seat to the various opportunities and issues the company faces" as a Visa board member since January 2014.

"I don't come in here expecting to make a lot of big changes," he said.

Scharf said in a letter to employees that he could no longer spend the time in San Francisco necessary to do his job properly and is resigning to spend more time with his family.

Visa's shares, which have more than doubled in value under Scharf's watch, were down 1.2 percent at $81.19 in after-market trading.

Kelly takes over at a time when Visa faces multiple challenges, including a federal appeals court decision in June to throw out a settlement with retailers that accused Visa and MasterCard Inc <MA.N> of improperly fixing credit and debit card fees.

Visa also has an ongoing legal battle with Wal-Mart Stores Inc <WMT.N> over the use of PINs to verify transactions made over the company's payment networks.

Kelly will have to look to consolidate Visa's position as the largest payments network operator in the world, even as non-traditional competitors such as PayPal Holdings Inc <PYPL.O> try to capture market share.

Kelly said on a conference call with analysts that he will be spending a significant amount of time in San Francisco, where Visa is headquartered, in addition to spending time in Europe to supervise integration with Visa Europe and in China.

Under Scharf, Visa closed a deal to combine with former unit Visa Europe in June.

Scharf has been CEO since November 2012, after working with JPMorgan Chase & Co's <JPM.N> retail banking business and its private equity arm.

"He has helped transform Visa .. into a technology-driven digital commerce company and has led a strategy that will benefit this company for years to come," Robert Matschullat, the company's independent chairman, said in a statement.

Kelly is also the CEO of Intersection Co, a firm partly owned by Sidewalk Labs, an Alphabet Inc <GOOGL.O> company.

(Reporting by Anya George Tharakan and Sudarshan Varadhan in Bengaluru; Editing by Maju Samuel and Leslie Adler)