In this work,the microscopic defects in Ti-Mo alloy hydrides were studied by using small-angle X-ray scattering (SAXS) technique. The results show that the SAXS intensity measured for hydride of 5at% Mo alloy was lower than that of other hydrides in the high scattering angle range. The crystal grains and its internal sub-structures in the hydrides are the scatterers which cause SAXS. The sub-structures are induced by the large number of dislocations in the hydrides produced during hydrogenation. The crystal structure of Mo 5at% alloy is mainly hcp,but that of the other alloys is bcc. The hydrides of all these alloys, however, have a fcc crystal structure. Therefore,it is indicated that the Ti-Mo alloys with hcp and bcc crystal structures form the same hydride structure,but induce different types of dislocation defects during hydrogenation.