Hydrogen adsorption properties of low-silica type X zeolites (LSX, Si/Al = 1) containing alkali or alkali-earth metal cations (Li+, Ca2+, and Mg2+) have been studied. It was found that the hydrogen adsorption capacities of LSX zeolites at 77 K were determined mainly by the porosity of the zeolite, while at 298 K, the storage capacities depended on both the H-2-cation interactions and the porosity. Among the three exchanged zeolites. Li-LSX had the highest H-2 capacity of 1.5 wt % at 77 K and 1 atm, and Ca-LSX had the highest capacity of 0.50 wt % at 298 K and 10 MPa. The hydrogen storage in LSX zeolites via spillover was also investigated. Three methods including bridge building with a catalyst, metal doping via incipient wetness impregnation and metal doping via chemical vapor deposition (CVD) were employed to induce hydrogen spillover, and enhance the storage capacities. Thus, the storage capacities were increased to 0.96-1.2 wt % on the Pt-doped zeolites at 298 K and 10 MPa. The differences between the three methods were compared and discussed. Furthermore, 5 and 10 wt % Ni were doped on Ca-LSX zeolite. The 10 wt % Ni-doped Ca-LSX zeolite showed a storage capacity of 1.15 wt % at 100 atm and 298 K. The important volumetric storage capacities of these zeolites were also estimated based on die densities of the densified zeolites. A 21 g/L portion was obtained for Pt-doped Ca-LSX, and 20 g/L was obtained for Ni-doped Ca-LSX, both at 298 K and 10 MPa. The high volumetric capacities were obtained because of the high densities of zeolites which are substantially higher (2-3 times higher) than that of carbons and metal organic frameworks.