In this work, we discuss the purification of hydrogen by physical adsorption on zeolites Li–LSX exchanged 78%, 83% and 99%. A newly developed adsorption device is applied to the gas–solid adsorption measurements. Isotherms of hydrogen adsorption are gravimetric volumetrically measured at 293.15 K up to 5 MPa. The accuracy of this new device is compared to NIST gas density data's of hydrogen and nitrogen at 293.15 K. Further the real density of the zeolites is obtained by helium skeleton density measurements at high temperature (650 K). The paper provides an interpretation of hydrogen adsorption capacities according to the gas-surface interaction. Further the isosteric heat of adsorption is obtained for the studied materials and analysed in relation to the zeolite cations exchange rate. Moreover, we discuss the influence of the ratio of cation exchange on hydrogen gas adsorption.