The structure and phase diagram of Ti_1−yV_yH_x (0≤y≤1.0, 0≤x≤2.0) have been studied by X-ray diffractometry at room temperature. The following crystallographic phases and their mixtures are identified and their phase boundaries are determined: α(hcp), β(bcc), γ(fcc), δ(fct) and ε(bct). One notable feature of this phase diagram is the presence of a wide β-monophase field in a Ti-rich region, where the terminal solubility of H is substantially enhanced. The change in stability of this β phase with V content is discussed in relation to the electronic band structure of this ternary system.