The electrochemical behaviour of zirconium metal and Ebonex(R) cathodes during the electrolysis of sulphite ions in sulphuric acid, at temperatures from 20 to 90 degrees C, is reported. The inactivity of these materials for the reduction of sulphite ions to sulphur is demonstrated, making the undivided cell oxidation of sulphite ions to sulphuric acid, at concentrations greater than 3.0 mol dm(-3), a viable process. The use of these two cathodes materials in conjunction with lead dioxide-coated and palladium oxide-coated anodes for sulphite ion oxidation is described. Linear sweep voltammograms, chronopotentiometry and batch electrolysis data are presented for sulphite ion oxidation and demonstrate the concept of an undivided electrolysis for the oxidation of sulphur dioxide in sulphuric acid.