The influence of the parent crystal structure on the hydrogenation of Ti 0.64 Zr 0.36 Ni alloy has been investigated. Austenitic Ti 0.64 Zr 0.36 Ni alloy with cubic CsCl-type structure preserves its metal sublattice structure after hydrogenation. It forms Ti 0.64 Zr 0.36 NiH 1.6 hydride (PH2=1 MPa and T=373 K) through a cell-volume expansion of 10.4%. On the contrary, the monoclinic TiNi-type structure of martensitic Ti 0.64 Zr 0.36 Ni alloy is modified after hydrogen absorption. At PH2=0.06 MPa and T=373 K, two hydrides coexist with orthorhombic CrB-type structure and compositions Ti 0.64 Zr 0.36 NiH and Ti 0.64 Zr 0.36 NiH 2.2 , which induces a cell-volume expansion of 5.36 and 18.3%, respectively. The stability of these crystal structures is discussed by comparison with other AB intermetallic compounds (A = Ti, Zr, Hf) and B = (Fe, Co, Ni).