The polycrystalline fine bulk samples of δ-phase Zr hydrides with various Hf contents were prepared and their thermal and mechanical properties were investigated. In the temperature range from room temperature to 973 K, the phase states were examined by high-temperature X-ray diffraction and thermogravimetry/differential thermal analyses. In the temperature range from room temperature to 673 K, the coefficient of linear thermal expansion, specific heat capacity, and thermal conductivity were evaluated. The Vickers hardness and sound velocity were measured at room temperature, and the elastic modulus was evaluated. The effects of Hf on the thermal and mechanical properties of Zr hydrides were studied.