The meeting was originally to last only 20 minutes but got stretched, official sources told IANS. Obama will visit New Delhi and Mumbai Nov 6-9.
Manmohan Singh ended his three-nation Asian tour here Saturday by taking part in the India-ASEAN and East Asia summits.
Also on a packed Saturday, he met Prime Ministers Julia Gillard of Australia, Lee Hsien Loong of Singapore and Nguyen Tan Dung of Vietnam.
He also called on Vietnam President Nguyen Minh Triet.
The prime minister will return home Saturday night. In his earlier leg, he visited Japan and Malaysia.