The phase structures and hydrogen storage properties of a Ti0.7Zr0.2V0.1Ni alloy are studied. It is found that this alloy consists of a matrix and a secondary phase. The matrix is a B2-type compound with bce structure and the secondary phase is a C14-type Laves phase with hexagonal structure. This alloy electrode has a larger charge-discharge capacity than stoichiometric TiNi electrodes but shows poorer activation behaviour. Optimizing the content of secondary phase is necessary for improving the overall hydrogen-storage properties of substituted Ti-Ni system alloys.