Process for producing liquefied hydrogen

A process for liquefying hydrogen gas comprising: initial cooling, usually called precooling, of H2 by means of indirect heat exchange with external nitrogen refrigerant in a first heat exchanger A, followed by further cooling and liquefaction of the said cooled hydrogen by means of heat exchange in a second heat exchanger B with hydrogen or helium and enclosing the heat exchangers necessary for the said precooling in a first thermally insulated container C, usually called a cold box enclosing the heat exchangers necessary for the further cooling and liquefaction in a second thermally insulated container D or cold box enclosing the said second thermally insulated container or cold box within the volume of the said first thermally insulated container.