CO impedes the low temperature (<170&DEG;C) oxidation of C3H6 on supported Pt. Supported Au catalysts are very effective in the removal of CO by oxidation, although it has little propene oxidation activity under these conditions. Addition of Au/TiO2 to Pt/Al2O3 either as a physical mixture or as a pre-catalyst removes the CO and lowers the light-off temperature (T-50) for C3H6 oxidation compared with Pt catalyst alone by &SIM;54&DEG;C in a feed of 1% CO, 400 ppm C3H6, 14% O-2, 2% H2O.