A process for producing compressed hydrogen gas including: electrolysing water to produce hydrogen gas, and compressing the hydrogen gas in a multistage compression system including: a centrifugal compression stage and a recycle system for recycling a portion of the hydrogen gas from a product end to a feed end of the centrifugal compression stage; wherein hydrogen gas feed is fed to the feed end at a pre-determined feed temperature and pressure and mole fraction of water; wherein a portion of the hydrogen gas is removed from the product end, reduced in pressure in the recycle system to the pre-determined feed pressure and is then recycled to form at least part of the hydrogen gas feed to the centrifugal compression stage; and further including cooling hydrogen gas comprising the reduced pressure hydrogen gas such that the water mole fraction in the hydrogen gas feed is at the pre-determined water mole fraction.