The results of studying InGaO3(ZnO)x (x = 4, 5) samples obtained by nitrate glycol gel combustion are reported. The effect of thermal treatment in the range of 300-1100 °C on the phase composition and surface morphology is investigated. It is found that the synthesis can yield nanoparticle agglomerates that are solid solutions of Ga and In oxides in ZnO with the wurtzite structure. Thermal treatment of the synthesized samples results in sintering of nanoparticles and the formation of ~1 µm macroparticles.