The aim of this work was to apply an experimental response surface methodology (RSM) to optimization of the Acid Yellow 36 (Ay 36) decolorization procedure the electro-Fenton process (EFP) using boron-doped diamond (BDD) electrodes. RSM was used for the evaluation of different operation parameters, process modelling, optimization study, and model prediction analysis. Optimization of the electro-Fenton process for decolorization of 60 mg L-1 of synthetic azo dye solution was analyzed using a central composite design (CCD) in RSM. The response variable for the experimental design was a percentage of the color removal. The three considered factors, at two different levels, were current density (j=8 and 23 mA/cm(2)), catalytic Fe2+ concentrations (0.1 and 0.3 mmol L-1), and electrolysis time (10 and 50 min). According to RSM, the optimum operation conditions were Fe2+ = 0.24 mmol L-1, j=23 mA/cm(2), and t=48 min. The maximal decolorization efficiency of 98% was achieved under these conditions. (C) 2010 Elsevier B.V. All rights reserved.