The purpose of this paper was to obtain nanosize GdAlO3 perovskite powders for catalyst applications. Two different thermal treatments (900 A degrees C for 1 h and 1000 A degrees C for 7 h) were applied to amorphous powder obtained by combined sol-gel and self-combustion method to promote crystallization of GdAlO3 perovskite. The structural and phase transformations after each thermal treatment have been studied by scanning electron microscopy (SEM), X-ray diffraction (XRD), and N-2 adsorption. After treatment at 900 A degrees C the formation of perovskite phase, GdAlO3 (with orthorhombic structure) in mixture with other phases (Gd2O3, Al2O3, Gd4Al2O9, and Gd3Al5O12) was detected. A monophase crystalline material, GdAlO3 pure perovskite, with crystallite size of 40 nm and S-BET of 10 m(2)/g was obtained after a longer treatment, 7 h at 1000 A degrees C. The catalytic activity of the two nanocrystalline samples in the combustion reaction of acetone, propane, benzene, and Pb free gasoline was studied. Both samples exhibit the best catalytic activity for acetone combustion (80 % acetone conversion at 500 A degrees C) and proved poor catalytic performance in catalytic combustion of Pb free gasoline (24 % conversion at 500 A degrees C). Although S-BET value for sample treated at 900 A degrees C is higher (22 m(2)/g) than that of the sample treated at 1000 A degrees C (10 m(2)/g), the treatment at 1000 A degrees C for 7 h assures a good thermo-chemical stability of GdAlO3 perovskite required by low temperature catalyst applications. GdAlO3 perovskite seems to be a promising catalyst for low temperature acetone combustion (T < 500 A degrees C).