We have investigated the photocatalytic activity for the decomposition of methyl orange on the pure LaCoO3 and metal ion doped LaCoO3 perovskite-typeoxides prepared using microwave process. In the case of pure LaCoO3 and cesium ion doped LaCoO3 catalysts, the formation of the perovskite crystalline phase was confirmed regardless of the preparation method. From the results of UV-Vis DRS, the pure LaCoO3 and cesium ion doped LaCoO3 catalysts have the similar absorption spectrum up to visible region. The chemisorbed oxygen plays an important role on the photocatalytic decomposition of methyl orange and the higher the contents of chemisorbed oxygen, the better performance of photocatalyst.