The implementation of fuel cell driven light vehicles may
represent an improvement of the quality of environment and
life, but one of the major technical problems for their
commercial introduction is represented by the onboard
hydrogen storage. The alternative solution to high pressure
vessels or liquid hydrogen reservoirs may consist in storing
hydrogen into solid absorbers which allow volumetric densities comparable or higher than liquid hydrogen and are intrinsically safe. Nanosized Mg hydride samples, mixed with suitable catalysts, are promising candidates for this purpose. Magnesium hydride powders mixed with 0.5 mol% of Nb2O5, with and without graphite, were ball milled in argon atmosphere. Hydrogen absorption/desorption tests, as well as pressurecomposition isotherms, were obtained on the treated material by a Sievert volumetric device. It is found that the coexistence of niobium pentaoxide and graphite improves the kinetics of MgH2 with respect to the literature data. Magnesium-rich Mg-Ni-Fe compounds were prepared by the melt spinning technique and subsequently ball milled for short times. Samples with similar composition were obtained by simply ball milling elemental powders. The hydrogen desorption kinetics were found better for the former samples than the latter ones. By Mossbauer spectroscopy measurements it is found that iron dissolves into the Mg2Ni lattice in the samples prepared by the melt spinning procedure, and that after multiple hydrogen absorption/desorption cycles the main part of iron separates from the Mg2NiH4 lattice.