In the current study, we report an extensive series of Grand Canonical Monte Carlo simulations of H2hydrates at pressures up to 500 MPa. The study examines the three most common hydrate structures (sI, sII, and sH). The average occupancy is calculated individually for each cavity by considering the enclathration mechanism as a process of gas adsorption in a porous solid. The correlation between chemical potential and pressure is determined throughNVTMonte Carlo simulations. Simulations are performed for three water models (SPC/E, TIP4P/Ice, and TIP5P); the effect of quantum behaviour of H2is also examined. In terms of engineering-type practical calculations, all of the examined models give similar results concerning the H2content of the hydrate. Finally, the calculated cage occupancy values are utilised for the prediction of H2content in hydrate systems with promoters (H2+ tetrahydrofuran) and an extensive comparison with experimental values is reported with good agreement between calculations and experiments. [ABSTRACT FROM PUBLISHER]