Magnesium hydride (MgH2) is a candidate material for hydrogen storage.MgH2-AlH3 composite shows superior hydrogen desorption properties than pure MgH2.However,this composite still suffers from poor cycling performance.In this work,NbF5 was utilized to improve the cycling properties of the MgH2-AlH3 composite.Cycling hydrogen desorption studies show that NbF5 significantly improves the cycling stability of MgH2-AlH3.The MgH2-AlH3-NbF5 composite can release about 2.7 wt％ of hydrogen at 300 ℃ for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt％ for more than 100 cycles.In comparison,the hydrogen desorption capacity of the MgH2-A1H3 composite is decreasing with the cycle number increasing.The capacity is reduced from a maximum value of 3.3 wt％ to about 1.0 wt％ after 40 cycles.Brunauer-Emmett-Teller (BET) surface area measurements show that the particle size of MgH2-AlH3 composite decreases after cycling,which means pulverization of the composite.NbF5 can to some extent suppress the pulverization of the composite during cycling,which partially contributes to the improvement of the cycling hydrogen desorption properties of the material.