Mg1-xCuxAl2O4 (x = 0-1.0) and Mg0.7M0.3Al2O4 (M = Mn, Co, and Ni) spinel-type catalysts with high surface areas were prepared. While a Cu-free MgAl2O4 spinel-type oxide showed no catalytic activity for the CO-O-2 reaction, the activity was significantly increased by the substitution of Mg (A-site) with Cu, and Mg0.7Cu0.3Al2O4 showed the highest catalytic activity under the practical conditions. The catalytic activities of Mg0.7M0.3Al2O4 (M = Mn, Co, Ni, and Cu) much depended on the kinds of M, and Cu was the best substituent metal. The catalytic activity of Mg0.7Cu0.3Al2O4 was much higher than those of La0.8Sr0.2CoO3 and LaMn0.6Cu0.4O3, which have been reported to be active for the CO-O-2 reaction. The highest catalytic activity of Mg0.7Cu0.3Al2O4 probably results from the easiest reducibility.