This study compared the electrochemical degradation of a model azo dye of methyl orange on the mixed metal oxide (MMO) and boron-doped diamond (BDD) electrode. The effect of several parameters such as current density, pH, electrolyte types, and initial dye concentration were investigated in terms of the decolorization, COD and TOC removal as well as the energy consumption. The dye degradation demonstrated different behaviors upon operative parameters on these two electrodes. Compared to the degradation on MMO, it performed better on BDD in wide operating conditions, and was proved to be more cost-effective and more suitable for dye mineralization. The presence of NaCl promoted the dye degradation on both electrodes, but varied in combustion efficiency, which decreased on the BDD but significantly improved on the MMO electrode. (C) 2011 Elsevier B.V. All rights reserved.