Abstract: The invention relates to an installation for liquefying hydrogen, comprising a circuit for hydrogen to be cooled, a set of heat exchanger(s) in heat exchange with the circuit, a cooling system comprising a refrigerator with a cycle of refrigeration of a first cycle gas comprising helium and/or hydrogen, the circuit comprising at least one catalysis section so as to ensure conversion of the ortho-hydrogen into para-hydrogen, the circuit further comprising a first bypass portion bypassing at least one catalysis section, the downstream end of the circuit comprising two parallel branches that are not combined and are supplied respectively with the hydrogen that has passed through the first bypass portion and hydrogen that has passed through the catalysis section so as to provide two distinct hydrogen streams that have different relative proportions of ortho-hydrogen and para-hydrogen.