The decolourisation of an azo dye, Reactive Black 5 (RB5), by an electrochemical technology was studied in both cubic and cylindrical cell configurations, each with a working volume of 0.4 L and graphite electrodes. Low decolourisation was detected in the treatment of pure solutions of RB5, but a significant extent of decolourisation was observed in the presence of Na2SO4. The extent of decolourisation was largely dependent on the cell configuration, and the best results were obtained when the cylindrical cell was employed. Nearly complete decolourisation was achieved in 3 h for an effluent containing 70 mg L-1 RB5 and 0.1 M Na2SO4, and the TOC removal was approximately 95%. In the presence of the non-inert electrolyte NaCl, complete decolourisation was detected. However, due to the chloro-organic compounds formed in the electrochemical oxidation with NaCl, the TOC removal in the most optimal conditions was approximately 93%. Furthermore, the efficiency of the cell configuration designs for the remediation of other organic compounds such as phenanthrene, a typical polycyclic aromatic hydrocarbon (PAH), has been demonstrated. (C) 2011 Elsevier B.V. All rights reserved.