A series of Ti-Zr-Hf-Mo-Nb high-entropy alloys with different Mo concentrations were developed as can-didate materials for hydrogen/tritium storage in solid phase.The crystal structures and hydrogenation properties of the Ti-Zr-Hf-Mo-Nb alloys were investigated by X-ray diffraction and differential scan-ning calorimetry techniques.All the alloys have a body-centred cubic single phase structure.The results demonstrate that the cell volume of the Ti-Zr-Hf-Mo-Nb hydride decreases with increasing Mo con-centration,which reduces their thermal stability.The theoretical calculation proposes that the lower binding energy of the Ti-Zr-Hf-Mo-Nb hydride decreases the thermal stability of Ti-Zr-Hf-Mo-Nb alloys with higher Mo content.The great hydrogenation performance for all the Ti-Zr-H f-Mo-Nb alloys is owing to their reversible single-phase transformation during the hydrogen absorption-desorption cycle,which would be beneficial to improving the hydrogen recycling rate and preventing the disproportionation.The compositional dependence of the hydrogenation performance of the Ti-Zr-Hf-Mo-Nb alloys was estab-lished and will be useful in designing novel hydrogen/tritium storage materials to satisfy the requirements of different application fields in hydrogen,solar thermal and nuclear energy.