The thermal expansion of a ZrO2-20 mol% Gd2O3 pellet has been systematically investigated using a thermo-mechanical analyzer in the temperature range of 293-1773 K. Variations in the thermal expansion coefficient and density upon temperature change were calculated using the thermal expansion data. The average linear thermal expansion coefficient of the ZrO2-20 mol% Gd2O3 pellet was found to be 9.522 × 10–6 K–1 in the range of 298-1073 K. This value is smaller than that of ZrO2 and larger than that of Gd2O3. Further, with an increase in temperature to 1773 K, the density of ZrO2-20 mol% Gd2O3 pellet was found to decrease to 94.98 % of the initial density at 293 K.