Heat is transferred from a flow of liquid hydrogen to a flow of a heat transfer fluid at a first heat exchanger to produce a warmed flow of pressurized hydrogen and a cooled flow of heat transfer fluid. Heat is also transferred at a second heat exchanger, to the cooled flow of heat transfer fluid, from a flow of pressurized hydrogen that is derived from one or more buffer vessels filled by the warmed flow of pressurized hydrogen and/or the warmed flow of pressurized hydrogen from the first exchanger to produce a cooled flow of pressurized hydrogen that is used to fill tanks of fuel cell electric vehicles.