Spherical Al2O3 and SiO2-Al2O3 supports with different silica contents have been synthesized by the oil column method. After impregnation with Na2PdCl4 solution and subsequent calcination, PdO/Al2O3 and PdO/SiO2-Al2O3 catalyst precursors were obtained. X-ray powder diffraction and low temperature N-2 adsorption-desorption measurements showed that the addition of silica increased the thermal stability, surface acidity, specific surface area and total pore volume of the spherical alumina. Temperature programmed reduction and H-2-O-2 titration indicated that Pd supported on the SiO2-Al2O3 spheres possessed higher dispersion and smaller particle size than that supported on pristine spherical Al2O3. Catalytic hydrogenation of ethylanthraquinone using molecular hydrogen was studied over the reduced Pd/Al2O3 and Pd/SiO2-Al2O3 catalysts with different silica contents. Under identical reaction conditions, the reaction activity and stability increased with increasing silica content. (c) Published by Elsevier B.V.