Cobalt oxide based catalysts were developed for carbon monoxide oxidation at low temperature. The catalysts were prepared by co-precipitation and calcined at 200 degrees C. Several techniques were used to characterize the catalysts, such as X-ray diffractometer system, N-2 physisorption measurements, scanning electron microscope (SEM), and X-ray photoelectron spectroscopy. Carbon monoxide oxidation studies were carried out to investigate the relation between the characteristic properties of the catalysts and the catalytic activity. Catalytic activity measurements were studied from room temperature to 200 degrees C, using a feed composition of 1% CO, 21% O-2, and remaining He. X-ray studies showed that the catalysts have an amorphous phase structure. The average pore diameter of the catalysts was in the mesopore diameter range. The pore sizes and pore volumes of the catalysts increased with increasing molar ratio of cobalt oxide in the catalysts. BET surface areas of the catalysts mostly depend on the cobalt oxide molar ratio in the structure of the catalysts. Low temperature CO oxidation activity measurements showed that the best activity was obtained from the 50/50 Co3O4/CeO2 catalyst, which has the light of temperature around 122 degrees C and yielded 100% CO conversion above 160 degrees C.