Supported gold catalysts on the mesoporous (MSP) metal oxides were prepared by a one-step, ultrasound-assisted reduction method, and characterized by XRD, HRTEM, EDX, BET, and XPS analysis. Their catalytic activities were examined in the oxidation of CO. Compared to the Au/Fe2O3(MSP) catalyst, the Au/TiO2(MSP) and Au/Fe2O3-TiO2(MSP) catalysts exhibited higher catalytic activity in the oxidation of CO at low temperatures. The high catalytic activity of Au/TiO2(MSP) was attributed to the metallic state of the gold nanoparticles, their small size (2-2.5 nm), and their high dispersion on the catalyst support.