Abstract: Thermogravimetry/differential thermogravimetric analysis of boron nitride (BN) nanomaterials showed possibility of hydrogen storage of 1–3 wt%. Possibility of hydrogen gas storage in BN and carbon (C) clusters was investigated by molecular orbital calculations. Chemisorption calculation of hydrogen for BN clusters showed that hydrogen bondings with nitrogenatoms and tetragonal rings were the most stable. Conditions of H₂ gas storage in B₃₆N₃₆ cluster, which was considered as a cap structure of B₉₉N₉₉ nanotube, were predicted by first principle single point energy calculations. H₂ molecules would beintroduced from hexagonal rings of the cage structure. Stability of H₂ molecules inside BN and C clusters was alsoinvestigated by molecular orbital calculations. C and BN clusters showed possibility of hydrogen storage of 6.5 and 4.9wt%, respectively. Chemisorption calculation was also carried out for B₂₄N₂₄ with changing endohedral elements in BNcluster to compare the bonding energy at nitrogen and boron, which showed that Li is a suitable element for hydrogenationto B₂₄N₂₄. BN fullerene materials would store H₂ molecule easier than carbon fullerene materials, and its stability for hightemperature would be good.