Lithium based materials are of great importance for the application of hydrogen storage with high gravimetric hydrogen densities. We have studied structural and hydriding properties of Li-B and Li-N based hydrides. In former case, correlation between B-H atomistic vibrations in [BH4] - -clusters and melting temperatures are investigated, with the comparison of those for MBH4 (M = Na, and K), which clarifies the effect of cation for destabilizing MBH4. In the latter case, the hydrogen desorption properties of LiNH2 and it's cation substitution system are preliminary examined. The starting and ending temperatures for the hydrogen desoprtion reaction are lowered about 50 K by the partial cation substitution of Li by Mg, due probably to the increase of the charge densities at [NH2]- -cluster site. These results provide a perspective for lowering the hydrogen desorption temperatures of complex hydrides.