Copper hexacyanoferrate (CuHCF) modified graphite electrode prepared by mechanical immobilisation method has been used for the amperometric determination of sulphite, which can be extended for the determination of SO 2 in air after absorbing the pollutant in sodium hydroxide solution. This method is based upon the electrocatalytic oxidation of sulphite by the modified electrode. The pH of the medium for oxidation should be in the range of 3.5-8.0. The range of determination of SO 2 is from 5.1 to 30.7 ppm. The presence of H 2 S with SO 2 will interfere in the determination. This can be eliminated by precipitating H 2 S as CuS.