A nanoporous material for adsorptive hydrogen storage under cryogenic conditions with a capacity of 2.18 wt% was identified. A remarkably high hydrogen storage capacity was found for the Metal-organic Framework Cu ₃(BTC). Theoretical studies indicate an optimum pore size or layer to layer separation for hydrogen adsorption in carbon-based adsorbents. It was observed that the bimodal pore size distribution and presence of smaller side pockets favored a high adsorption capacity. The results show that the storage capacity is higher than that of IRMOFs and other coordination polymers and only surpassed by MOF-505.