London: Dec 15; The ex-helicopter pilot - with American Tim Kopra and Russian Yuri Malenchenko - will launch on a Russian Soyuz rocket at Baikonur Cosmodrome, in Kazakhstan.
Mr Peake is the first official UK astronaut. Previous "British" astronauts have either had US citizenship and worked for Nasa or been privately funded.
On the ISS he will conduct experiments.
He will also carry out educational activities designed to get young people interested in science.
Fuelling of the rocket has begun ahead of the launch - set for 11:03 GMT - from Site 1 at Baikonur, the pad where Yuri Gagarin made the first historic human spaceflight in 1961.