The 'Skyscraper' singer - who entered rehab last November for three months to receive treatment for her eating disorders and self-harming - went into the studio with the producer yesterday (25.07.11) to record a duet, six months after he said he wanting to collaborate with her.
Demi told her fans on twitter: "Going into the studio with @Timbaland. You guys ready?! (sic)"
Following their first session, Timbaland wrote: "Yo @ddlovato you killed dat song i gave u. I just pick 2 more for you from one of the producer out my camp @wizz_dumb for u to do 2morrow. (sic)"
The producer's younger brother Sebastian Mosley wrote: "Demi (@ddlovato) is killing it in the booth singing right now. Girl's got a serious voice on her."
In January, Timbaland said the 18-year-old starlet was "amazing" and posted a video message on YouTube, saying he wanted to work with her and had even penned a song with her in mind.