Three kinds of metal hydride, Zr hydrides, Gd hydrides, and the hydrides of Zr-Gd alloys (Zr:Gd=10:1, 8:1, 6:1), were prepared and their mechanical and thermal properties were examined. It was confirmed that the hydrides of Zr-Gd alloys were composed of mixtures of Zr hydrides and Gd hydrides. We succeeded in formulating empirical equations describing the density, Vickers hardness, Young's modulus, heat capacity, and thermal diffusivity of the hydrides of Zr-Gd alloys.<br>