Rates of SO2 reduction with CO on single beds of Fe/SiO2, Fe/Al2O3 and Fe/SiO2/Al2O3 catalysts were measured. Under comparable conditions, the SO2 reduction was much greater when both Fe and Al2O3 were present. The results could not be explained on the basis of additivity of the separate catalytic contributions of the individual components of the mixtures. Experimental data indicate that a cooperative effect between the Fe and Al2O3 component is involved. The exhaust SCO concentration from a single catalyst layer containing Fe was still quite large at 400 °C. However, when a second layer of pure Al2O3 was present, the SCO exhaust concentration decreased by a factor of ten. These results suggest that a SCO intermediate is first formed on the Fe site. This intermediate then is removed by the alumina component which acts as a catalyst for the SCO-SO2 reaction. The stepwise reactions at separate active centers explain why both Fe and Al2O3 are needed to catalyze the reduction of SO2 with CO to yield elemental sulfur and CO2.