The feasibility of removing sulfur dioxide by carbon monoxide reduction in a fixed-bed catalytic reactor was investigated. Maximum catalytic activity was obtained with about 40 percent iron- alumina mixture with a nominal gas mixture of 10 percent carbon monoxide, 5 percent sulfur dioxide, and the balance nitrogen. The synergistic effect of this catalyst mixture was explained by a dual reaction site mechanism, with both iron and alumina augmenting their specific sites at their interparticle contacts. The catalytic activity also increased with decreasing catalyst pellet size. The apparent activation energy of the reaction was 18.3 Kcal per mole in the temperature range of 350 deg to 600 deg c. Carbonyl sulfide (cos) was produced by the interaction of carbon monoxide and sulfur. The amount decreased with decreasing CO concentration. The ratio of cos formed per so2 removed reached a maximum at about 400 deg c. The reaction rate appeared to be independent of so2 concentration in the range of 0.2 to 16 percent. The rate, however, increased directly with the CO concentration in the range of 5 to 20 percent. The presence of co2 (<15 percent) had no appreciable effect on the rate. However, not over 0.5 percent oxygen could be tolerated. This method appears feasible for removing so2 from waste gas if the oxygen is removed prior to the catalytic so2 reduction process.