A detailed study oil the electrochemical oxidation of aqueous solutions of Remazol Brilliant Blue Reactive on a boron-doped diamond electrode is presented. Electrolyses, conducted Under galvanostatic conditions, were monitored evaluating the removal of colour, chemical oxygen demand and total organic carbon. The influence of the supporting electrolyte, Current density, initial dye concentration, temperature and pH is discussed. Colour removal was found to be dependent mostly on the chloride concentration suggesting the involvement of electrogenerated active chlorine in the reaction of discolouration. Rate constants Calculated from colour decay versus time revealed a zero order reaction up to 150 mg L-1 in dye. The degradation efficiency was directly related to the dye concentration thus indicating that oxidation and mineralisation occurred under mass transfer control. Using 0.01 M chloride, under mild operating conditions of pH, temperature and current density, the treatment proposed enabled to achieve complete discolouration and total mineralisation of Remazol Brilliant Blue solution in a range from 50 to 150 mg L-1. (C) 2009 Elsevier B.V. All rights reserved.