Mg and Mg-based alloys are regarded as strong candidate hydrogen storage materials since their hydrogen capacity exceeds that of known metal hydrides. One of the approaches to improve kinetic is addition of metal oxide. In this paper, we tried to improve the hydrogenation properties of Mg-based hydrogen storage composites. The effect of transition metal oxides, such as Nb2O5 on the kinetics of the Magnesium hydrogen absorption kinetics was investigated. MgHx-5wt.% Nb2O5 composites have been synthesized by hydrogen induced mechanical alloying. The powder fabricated was characterized by X-ray diffraction (XRD), Field Emission-Scanning Electron Microscopy (Fe-SEM), Energy Dispersive X-ray (EDX), BET and simultaneous Thermo Gravimetric Analysis / Differential Scanning Calorimetry (TG/DSC) analysis. The Absorption / desorption kinetics of MgHx-5wt.% Nb2O5 (type I and II) are determined at 423, 473, 523, 573 and 623 K.