A 10%Co/ZrO2 catalyst prepared by impregnation was tested for its activity for the oxidation of CO to CO2 in excess oxygen. Activity tests showed that conversion could be obtained at temperatures as low as 20 degrees C. Time-on-stream studies showed no loss of activity in these experiments, indicating that this catalyst is stable in the experimental oxidizing conditions. The activation energy for the CO to CO2 oxidation reaction was calculated as E-a = 54 kJ/mol over this catalyst. Characterization of the material by thermogravimetric analysis, temperature-programmed techniques, X-ray photoelectron spectroscopy, and laser Raman spectroscopy indicate that Co3O4 is present on monoclinic ZrO2 after the calcination of the catalyst.