FIELD: metallurgy. SUBSTANCE: invention relates to methods for producing composite powder materials by hydrometallurgical method, namely, to compositions based on stabilized aluminum oxide and a solid solution of cerium and zirconium oxides, which can be used as carriers of the catalytically active phase in an automotive catalytic unit. A method for synthesizing a composition based on aluminum oxide and a solid solution of cerium and zirconium oxides includes the preparation of an aqueous suspension of cerium, zirconium and possibly yttrium or lanthanum hydroxides with a pH of 7 to 10 with the addition of ammonia at room temperature, the preparation of an aqueous suspension of aluminum hydroxides and possibly zirconium or lanthanum at room temperature. Next, the resulting suspensions are mixed at room temperature to produce a total suspension. The precipitate is separated from the mother liquor and isopropyl alcohol is injected. The mixture is dried and burnt. Before separating the precipitate from the mother liquor, the total suspension is ground so that the D90 value is less than 9.5 mcm, or subjected to hydrothermal treatment at a temperature above 110°C with the duration of 0 hours or more. EFFECT: increase in the thermal stability of the surface of the particles of the composite powder material is provided. 8 cl, 1 dwg, 6 ex.