It's been used successfully for space travel, in liquid (cryogenic) form. The Space Shuttle's main engines ran on hydrogen fuel, for example. However the lates

It's been used successfully for space travel, in liquid (cryogenic) form. The Space Shuttle's main engines ran on hydrogen fuel, for example. However the latest generation of rockets seems to have moved away from hydrogen back to things like RP-1 (kerosene) and liquid methane. The high cost and difficulties of working with hydrogen is a factor in this.