The destruction and colour removal of methylene blue were carried out by mediated electrochemical oxidation using cerium(IV) mediator in nitric acid medium using two-phase system and was applied for oxidation of organic compound. Organic compounds and mediator were taken in the organic and aqueous phases respectively. The influence of organic solvent type, cerium(III) concentration, dye concentration, stirring speed and temperature were investigated in order to find the optimum conditions of the system to check the removal of COD and colour in the organic phase. The decolourisation followed the pseudo-first order reaction for electrochemically oxidized cerium(IV). The maximum colour removal efficiency of 95% was achieved within 45 min in dichloromethane solvent system. The COD removal efficiency and colour removal rate were increased with increase in temperature and stirring speed. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.