|Ryan Lochte of the U.S. reacts after winning the men's 200m backstroke final during the World Swimming Championships at the Sant Jordi arena in Barcelona August 2, 2013. REUTERS/Albert Gea|
The decorated 28-year-old clocked a time of one minute 53.79 seconds, with Radoslaw Kawecki of Poland taking silver in 1:54.24 and Lochte's compatriot, Olympic champion Tyler Clary, bronze in 1:54.64.
Lochte, who won 200 metres individual medley gold on Thursday, is only the second man to win three 200 backstroke titles after compatriot and world record holder Aaron Peirsol, who won four in 2001, 2003, 2005 and 2009.
Lochte was champion in 2007 and at the last world championships in Shanghai two years ago.
(Reporting by Iain Rogers, editing by Ed Osmond)