Here we report the thermal properties and cycling performance of Ca(BH4)(2)/MgH2. The reaction enthalpy is 48 kJ mol (1) H-2 and equilibrium pressure at 350 degrees C is 0.4981 MPa. We add NbF5 into Ca(BH4)(2)/MgH2 to figure out the degradation mechanism because of its catalytic ability. Ca(BH4)(2)/MgH2 follows the dehydrogenation path to form CaH2, CaB6 and Mg. The degradation of Ca(BH4)(2)/MgH2 composite during cycling is due to the particle aggregation and the reduction of CaB6 product. NbF5 can promote the forming of CaB6 and prevent microstructural coarsening in Ca(BH4)(2)/MgH2 during cycling, which leads to better reversibility. (C) 2018 Elsevier B.V. All rights reserved.