The former Spice Girls star is training for the running, swimming and cycling endurance race in London in July (11) - and she's appealing for sponsors to generate money for Sparks, a U.K. medical research organisation which helps sick kids.
In a post on her fundraising page, she writes, "On July 30th, I will be taking part in the Virgin Active London Triathlon to raise money for the children's charity Sparks. The course includes a 750m swim, a 20k bike ride and a 5k run.
"I really appreciate all your support and thank you for any donations."
Melanie Chisholm already has one big name supporting her - the star's When You're Gone collaborator Bryan Adams has donated $320 (£200).
In a post on her Twitter.com page, the singer writes, "Hey Bry. Thank you so much for your generous donation."