In an attempt to find a substitute to noble-metal based catalysts in the catalytic converters for the removal of CO from automotive exhaust, non-noble metal based catalysts of perovskite based oxides were tested. Perovskites of the structure ABO(3): where A cation had La, Ba or Ca and B cation had Co or Fe were used for the reaction. Substituted perovskite of the form A(1-x)A ' xBO3, where A ' was Ce metal, was also used. The perovskite catalyst were tested in unsupported as well as supported forms. The supports used were zirconia, ceria or a mixture of the two in different proportions. The results indicate that among the unsupported catalysts, LaCoO3 is the best. Among the substituted catalysts, La0.3Ce0.7CoO3 gave the best performance showing 100% CO conversion at 200 degreesC. The support, zirconia (20%) and ceria (80%) mixture was found to be the best combination. The durability runs up to 6 h show the activity pattern in the order : La0.3Ce0.7CoO3> La0.6Ce0.4CoO3> LaCoO3.