From chess.com:
On Monday night in Tallinn (Estonia) Garry Kasparov announced his candidacy for the 2014 FIDE Presidential Elections. The 13th World Champion aims to “revitalize FIDE with a focus on serving the national federations and raising the commercial profile of chess worldwide.”
They also have an exclusive interview with Kasparov about the decision.
The current president, Kirsan Ilyumzhinov, has been on the position since 1995.