Carbon mono oxide (CO) and unburnt hydrocarbons (UHC) are major pollutants emitted from spark ignition engine, which are hazardous and cause health problems to human beings and hence control of these pollutants call for immediate attention. Experiments are carried out for controlling the pollutants from a variable- compression ratio, spark ignition engine with gasoline fitted with catalytic converter containing sponge iron catalyst. The influence of catalytic converter parameters such as void ratio, amount of air injected into the catalytic converter, temperature of injected air on these emissions at different speeds and compression ratios of the engine is studied. The speed of the engine has marginal effect, while load and compression ratio have strong influence on reduction of pollutants. Air injection drastically decreased the pollutants, which is further pronounced with the rise of temperature of injected air. The engine with catalytic converter decreased the exhaust emissions considerably when compared to conventional engine without catalytic converter.