The article investigates the influence of hydrothermal action on the physical and mechanical properties of ceramics ZrO2 - 3 mol. % Y2O3. A comparison of the properties of samples sintered at 1350 °C in an air atmosphere and at 1850 °C in a vacuum, followed by oxidative annealing at 1200 °C in an air atmosphere, is carried out. It has been shown that the characteristics of specimens sintered at 1850 °C practically do not change after hydrothermal treatment, whereas in specimens sintered at 1350 °C, there was a significant drop in strength and hardness, by about 40-50 %.