Britney Spears "was like a little kid" in the recording studio with will.i.am.
The Black Eyed Peas star wrote the track 'Big Fat Bass' for Britney's new album 'Femme Fatale' and loved working with her because her enthusiasm was infectious.
He said: "I discovered her love for music. I have never seen anyone, like, come alive, full of excitement and giggling and laughing behind the mic.
"She was like a little kid when she was recording the song and it just brought the whole atmosphere, it changed the whole atmosphere when someone really loves music. So it was great working with her."
Despite Britney's enthusiasm, will.i.am said she is also completely professional and didn't any advice from him.
He added to MTV: "When someone's excited to go out and just do it, what advice? You don't need no advice. She is like, 'When I say on the song, "You all better get ready for the kick drum,"' she was already anticipating what she was going to do onstage when that beat broke down.
"Adding that type of perspective, when we were recording it, you don't need to give nobody like Britney advice."
Meanwhile, will.i.am and the other members of the Black Eyed Peas - Fergie, Taboo and apl.de.ap - have announced plans to open a school for New York teenagers to learn video and music production through their charitable organisation, The Peapod Foundation.
will.i.am said: "Our passion for music and media was fuelled by many generous people on our road to success. Expanding the network of Peapod Adobe Youth Voices academies enables us to pay it forward, giving more youth the skills and encouragement they need to realise their dreams."