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The paper examines the properties of the nanocrystalline powder 95 mole% ZrO 2 -2 mole% CeO 2 -3 mole% Y 2 O 3 , synthesized using a combination of two methods: coprecipitation and hydrothermal decomposition. It is established that coprecipitation produces an x-ray amorphous gel consisting of hard agglomerates from 5 to 10 μm and having a specific surface area of 120 m 2 /g and a bottle density of 2.94 g/cm 3 . Hydrothermal synthesis results in a low-temperature metastable cubic solid solution based on ZrO 2 (F-ZrO 2 ). Its specific surface area is 101.6 m 2 /g and bottle density is 4.65 g/cm 3 . Soft agglomerates (0.5-10 μm) consist of primary particles with sizes to 10 nm. The change in hydrothermal suspension processing steps results in soft agglomerates with branched internal porosity. This method allows synthesizing powders of needed compositions in the ZrO 2 -CeO 2 -Y 2 O 3 system. Keywords: zirconia, nanocrystalline powder, hydrothermal synthesis, metastable solid solution.The bioinertia, high strength, and high fracture toughness of ceramics based on stabilized zirconia stimulated studies intended to create various bioimplants. Researchers focus on the ZrO 2 -Y 2 O 3 system as the basis for obtaining fine-grain and high-strength materials, i.e. Y-TZP (tetragonal zirconia polycrystal). These materials are currently used to produce prostheses of femoral heads [1,2].The adequate lifetime of Y-TZP-based ceramic bioimplants results from their resistance to slow crack growth and in vivo ageing effect. The ageing is caused by the phase transition of zirconia from tetragonal to monoclinic modification (T-ZrO 2 → M-ZrO 2 ) found, as a rule, on the ceramic surface. The transition may occur during sterilization of bioimplants. This phenomenon is accompanied by the expansion of the material and microcracking of its surface; which, in turn, impair mechanical properties and, ultimately, cause the degradation of bioimplants [3][4][5]. It is established that CeO 2 additives contribute to the Y-TZP resistance to low-temperature ageing in a humid environment. The partial replacement of cerium oxide with yttrium oxide in Ce-TZP reduces the grain size and enhances the thermodynamic stability of T-ZrO 2 [6-10]. In addition, material whose critical coefficient of fracture toughness exceeded 25 MPa ⋅ m 0.5 was obtained in the ZrO 2 -CeO 2 system [11]. Therefore, complex alloying of ZrO 2 with yttrium and cerium oxides can increase its fracture toughness, yet reduce the adverse effect of the humid environment on the strength characteristics. Thus, it is natural that researchers are so interested in developing ZrO 2 -Y 2 O 3 -CeO 2 -based materials.The metastable tetragonal phase in Y-TZP is known to exist for a long time needed for proper functioning of the main joint if the following requirements are met when the powder is synthesized, formed, and thermally treated. First, when the initial powders are synthesized they should be optimally alloyed with the needed amount of additives uniformly distributed over ZrO 2 . Second, bill...