Abstract: In a process for the recovery of hydrogen from compressed purge gas withdrawn from a recyling gas stream of an ammonia synthesis wherein the hydrogen is separated from the purge gas by partial condensation at cryogenic temperatures, refrigeration is provided by expanding and evaporating the condensate so formed, and the partial pressure of the expanded condensate is lowered by withdrawing a bleed stream from said uncondensed gas, expanding said bleed stream and injecting it into said expanded condensate, condensation of nitrogen employed to purge the cold box for the cryogenic process is avoided by either injecting into the bleed stream a warmer gas provided from the uncondensed gas and/or the purge gas or expanding the condensate and bleed stream in stages with separate expansion thereof in an initial stage and injection of the bleed stream into the condensate prior to the final stage.