Catalysts play a critical role in improving the hydrogen storage kinetics in Mg/MgH2 system.Exploring highly efficient catalysts and catalyst design principles are hot topics but challenging.The catalytic activity of metallic elements on dehydrogenation kinetics generally follows a sequence of Ti ＞ Nb ＞ Ni ＞ V ＞ Co ＞ Mo.Herein,we report a highly efficient alloy catalyst composed of lowactive elements of Mo and Ni (i.e.MoNi alloy) for MgH2 particles.MoNi alloy nanoparticles show excellent catalytic effect,even outperforming most advanced Ti-based catalysts.The synergy between Mo and Ni elements can promote the break of Mg-H bonds and the dissociation of hydrogen molecules,thus significantly improves the kinetics of Mg/MgH2 system.The MoNi-catalyzed Mg/MgH2 system can absorb and release 6.7 wt.％ hydrogen within 60 s and 10 min at 300 ℃,respectively,and exhibits excellent cycling stability and low-temperature hydrogen storage performance.This study provides a strategy for designing efficient catalysts for hydrogen storage materials using the synergy of metal elements.