The contracts now show that traders see about a 55 percent chance that the first Fed rate hike will come in September 2015, based on CME FedWatch, which tracks rate hike expectations using its Fed funds futures contracts.

Before the minutes were released, traders assigned September 2015 a 59 percent chance of marking the start of the Fed's first rate hike cycle in a decade.

The minutes reflected a vibrant debate over the outlook for inflation and the economy at a meeting where policy-makers decided to finally end their controversial bond-buying stimulus.

The Fed has kept short-term rates near zero since December 2008.

(Reporting by Ann Saphir; Editing by James Dalgleish)