Bosses at the American Foundation for AIDS Research (amfAR) have thanked KATY PERRY after the pop star agreed to donate a guitar to the charity's upcoming auction.

The I Kissed a Girl hitmaker pledged to let the organization add the instrument to its fundraising drive on Friday (12Oct12), and she promised to increase its potential value by signing it with a personal dedication to the winning bidder.

AmfAR bosses were so impressed with Perry's generosity, they reached out to thank her in a message posted on the charity's Facebook.com page.

The post reads, "We're thrilled to announce that superstar Katy Perry has donated a guitar to auction off at amfAR's Inspiration Gala Los Angeles tomorrow. Katy will personalise an autograph on the guitar to the lucky winner. All proceeds benefit our research programs... Thank you, Katy!"