As a study on the treatment of exhaust gases from a methanol-fueled vehicle, catalytic oxidation of formaldehyde and methanol on perovskite-type oxides was performed. La_0.8Sr_0.2MnO₃, La_0.8Sr_0.2CoO₃, YBa₂Cu₃O₇ (superconductor), and ErBa₂Cu₃O₇ (superconductor) were used as catalysts. La-based catalysts were prepared by a citrate method and calcined at 650°C, 800°C, and 900°C, respectively. The catalytic activity of La-based catalysts increased with the increase in the surface area that was dependent on the calcination temperature. Superconductive oxides were also prepared by a citrate method and calcined at 920°C. The catalytic activity of ErBa₂Cu₃O₇ was found to be better than that of YBa₂Cu₃O₇. For La-based perovskite calcined at 650°C, the catalytic activity of La_0.8Sr_0.2MnO₃ was higher than La_0.8Sr_0.2CoO₃. Calcining at 800°C and 900°C, however, the catalytic activity of LLa_0.8Sr_0.2 CoO₃ was higher than La_0.8Sr_0.2MnO₃.