He launched on April 7, 2007 (GMT), on board Soyuz TMA-10. He shared a ride with two Russian cosmonauts to the International Space Station, and returned aboard Soyuz TMA-9, landing on April 21, 2007.
Upon arrival to the ISS on April 9, 2007, Simonyi said, "It is amazing how it appears from the blackness of the sky. It was very, very dramatic. It was like a big stage set, a fantastic production of some incredible opera or modern play. That's what I was referring to when I said I was blown away."
Simonyi's expected return on April 20, 2007, was delayed by one day due to 'boggy ground'. He returned to Earth on April 21, 2007 along with an American astronaut and a Russian cosmonaut.
Charles Simonyi is a licensed amateur radio operator with the call sign KE7KDP, and planned to contact a number of schools while on his flight on the International Space Station using amateur radio for the communication with those schools. On April 11, 2007 the American Radio Relay League reported that Simonyi was already making ham radio contacts from space.