Former US president George H.W. Bush was released from hospital on Monday following more than two months of treatment for bronchitis, a bacterial infection and a persistent cough.

"Mr. Bush has improved to the point that he will not need any special medication when he goes home, but he will continue physical therapy," said physician Amy Mynderse.

Bush, at 88 the oldest surviving former president, was admitted to the Methodist Hospital in Houston on November 7 and released after 12 days only to be readmitted four days later when his cough flared up again.

"I am deeply grateful for the wonderful doctors and nurses at Methodist who took such good care of me," Bush said in a statement after being picked up by his wife Barbara shortly after noon local time (1800 GMT).

"Let me add just how touched we were by the many get-well messages we received from our friends and fellow Americans. Your prayers and good wishes helped more than you know, and as I head home my only concern is that I will not be able to thank each of you for your kind words."

Bush's spokesman Jim McGrath told AFP that the former president and his wife had returned immediately to their home in west Houston where he would continue to receive "some strength training or conditioning."

Calling it a "wonderful day" for the ex-president, the spokesman said Bush had understood the need to be in hospital but was delighted to be out.

"He's not a man whose known to enjoy to sit still for too long, and as along as he didn't need to be in the hospital he wanted to get out. He's a very happy former president today," McGrath added.

No more tests were scheduled but the spokesman said they would "take these things one day at a time."

Doctors had hoped to have the elder statesman home for Christmas, but he was instead forced to spend the holiday season in the hospital, where he was joined by his wife Barbara, son Neil and grandson Pierce.

Bush, a Republican, served only one term in the White House, from 1989 to 1993, despite sending US troops to victory in the first Gulf War in which an American-led coalition expelled Saddam Hussein's invading forces from Kuwait.

Bush, a decorated World War II veteran, had earlier served in several top government posts, including as vice president to Ronald Reagan, director of the Central Intelligence Agency, and as US ambassador to the United Nations.

He was also chief of the US Liaison Office in China when Washington had official ties with Beijing's foe Taipei.

His son George W. Bush served two terms as president and also went to war with Iraq, this time sending US-led troops all the way to Baghdad to overthrow Saddam, whom he had wrongly accused of hoarding weapons of mass destruction.