The 35-year-old singer - who quit the pop group in 1995 - spent five hours in a Los Angeles studio on Tuesday (26.01.10) singing and recording songs with his old bandmates and was then spotted hugging each of them as he left.
A source told The Sun newspaper: "All the signs are looking good. It's great news for the fans. They're using this time in Los Angeles to start working together as a band again.
"They were delighted with Tuesday's session and were congratulating each other as they left. They're using this time together to crack on with reunion songs."
Take That - Gary Barlow, Howard Donald, Mark Owen and Jason Orange - were in the US city to record their parts for Simon Cowell's charity single, which is set to raise funds for the relief effort for Haiti's earthquake victims.
A spokesman for Take That last night (27.01.10) said: "Take That didn't go to Los Angeles with plans to officially write or record with Robbie, but they've been hanging out together, which is great."