Defense Secretary Robert M. Gates passed the command's flag from outgoing commander Navy Adm. William J. Fallon to Dempsey at MacDill Air Force Base near Tampa, where the Central Command is based, the department said in a news release.
Gates said Fallon had a positive impact as Central Command's commander. Fallon announced his retirement March 11, citing the perception that he disagreed with the Bush administration over Iran.
"Under Admiral Fallon's command, the last year in CENTCOM's area of operation has been one of great progress on a number of fronts," Gates said, citing reduced levels of violence in Iraq and decreased Taliban influence in Afghanistan.
Gates praised Dempsey's ability to temporarily lead Central Command.
"I am confident that he is prepared to lead CENTCOM," Gates said of Dempsey. "His extensive experience on the ground there will be of great value in the coming months."
U.S. President George Bush has nominated and the Senate has confirmed Dempsey, a three-star general, to take command of U.S. Army, Europe, when he leaves the Central Command post.