Catalytic performance of a series of Ga2O3-Al2O3 mixed oxides prepared by alcoholic-coprecipitation method for the dehydrogenation of propane in the presence of CO2 was investigated. It is shown that the combination of Ga and Al oxides greatly improved the performance of the Ga2O3-based materials for catalytic dehydrogenation of propane, with the highest performance attainable at a Ga2O3-Al2O3 catalyst with a 20 mol% aluminum content. While the same tendency was observed for the specific activity normalized by BET surface area, significantly enhanced stability was achieved for Ga2O3-Al2O3 with higher aluminum content. X-ray diffraction (XRD) revealed that a homogeneous spinel-type Ga2O3-Al2O3 solid solution is uniformly formed by substitution of Ga3+ for Al3+ in the Al2O3 lattice. The enhanced activity of Ga2O3-Al2O3 mixed oxides was accounted for by the abundance of surface weak acid sites due to the synergetic interaction between Ga2O3 and Al2O3 in the solid solution systems.