A new hybrid nanocatalyst Ni-CeOx/GNS (graphene nanosheets supported nanoscale Ni and CeOx., x = 1.69) of high surface area and porosity is synthesized by impregnation reduction method. It is demonstrated that the Ni-CeOx/GNS nanocatalyst exhibits improved catalytic effect on the dehydrogenation performances of MgH2 compares to individual Ni/GNS, CeOx/GNS, or GNS. Differential scanning calorimetry psq measurement proved that both the onset and peak desorption temperature of MgH2-5 wt% Ni-CeOx/GNS (abbreviated as MgNCG) nanocomposites can be decreased by 90.2 and 60.1 degrees C, respectively. Isothermal desorption kinetic test confirmed that the dehydrogenation kinetics of MgNCG nanocomposites is dozens of times higher than the pure milled MgH2, e.g. MgNCG nano composites can release 6.50 wt% H-2 within 10 min at 300 degrees C with an initial hydrogen pressure of 5 KPa, superior to 0.16 wt% H-2 desorbed by MgH2 under the same condition. Additionally, the activation energy (Ea) of MgNCG decreases significantly contrast with pure milled MgH2, it is proposed that the tri-component of Ni-CeOx/GNS nanocatalyst has a synergistic effect on the highly efficient dehydrogenation of MgH2. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.