"(Manmohan) Singh was the primary partner while we were working during the financial meltdown (of 2008)," Mr Obama said at the Hindustan Times Leadership Summit, admiring a "great" friend who laid the foundations of modern Indian economy.
He also praised Prime Minister Narendra Modi for his efforts to modernise Indian bureaucracy, saying he was "the primary partner during the making of Paris (climate) accord".
"I like him," Mr Obama replied when he was asked about PM Modi. "I think he has a vision for the country... He is modernising elements of bureaucracy."
"I was also great friends with (Manmohan) Singh... When you look at the steps Singh took to modernising the economy, it was the foundation for modernising Indian economy."
He said both Dr Singh and PM Modi were "sound leaders".