NOVELTY - The method of preparing hydrogen at a re-fueling site for adsorbing hydrogen on a body of adsorbent particles contained within an on-vehicle storage tank of a vehicle, comprises providing hydrogen gas from a source of compressed gas at a pressure in excess of 155 bar, cooling the gas by heat exchange with liquid nitrogen to a temperature of 80 K, further cooling the gas by an isenthalpic expansion at a temperature below 70 K and a pressure of 10-30 bar, and circulating a stream of the further cooled hydrogen into and from contact with the body of adsorbent particles.    USE - The method is useful for preparing hydrogen at a re-fueling site for adsorbing hydrogen on a body of adsorbent particles contained within an on-vehicle storage tank of a vehicle, where the hydrogen is useful for a fuel cell or other hydrogen-consuming power plant or device.    ADVANTAGE - The method is capable of easily, rapidly and economically preparing hydrogen at a re-fueling site thus ensuring efficient absorption of hydrogen on adsorbent particles of a hydrogen powered vehicle at desirable pressure and temperature conditions.    DETAILED DESCRIPTION - The method of preparing hydrogen at a re-fueling site for adsorbing hydrogen on a body of adsorbent particles contained within an on-vehicle storage tank of a vehicle, comprises providing hydrogen gas from a source of compressed gas at a pressure in excess of 155 bar, cooling the gas by heat exchange with liquid nitrogen to a temperature of 80 K, further cooling the gas by an isenthalpic expansion at a temperature below 70 K and a pressure of 10-30 bar, and circulating a stream of the further cooled hydrogen into and from contact with the body of adsorbent particles. Some of the hydrogen is adsorbed on the particles from the circulating hydrogen stream. The stream is heated by the body of particles, as hydrogen is adsorbed on them. Some of the circulated hydrogen is again cooled by heat exchange with liquid nitrogen, further cooled to a temperature below 80 K, and recirculated into contact with the body of hydrogen adsorbent particles. The hydrogen is recirculated until a desired adsorbed hydrogen content of the body is attained.    DESCRIPTION OF DRAWING(S) - The figure shows a graph of fueling time versus hydrogen feed flow rate to a 90 kg bed of a typical metal-organic framework (MOF).