Abstract: The volume expansion of hydrogen absorption and hydride thermostability of Ti 87.5Hf 12.5 alloy was determined. A comparison of these properties was performed between TiHf alloy and Ti, TiZr, TiV and TiNb alloy, and it is seen that TiHf alloy has the smallest volume expansion and the highest eutectoid reaction temperature. Addition of Hf swells the unit cell of TiH2 obviously. Hydrogen absorption and desorption dynamics and PCT properties of TiHf alloy was determined. The hydrogen absorption enthalpy of TiHf alloy is only a little higher than that of Ti.