Abstract The aim of this research was to remove COD and color from a hazardous municipal landfill leachate using electro-Fenton process. The effects of four important parameters including H2O2/Fe2+ molar ratio, current density, pH and reaction time on the process were carefully considered. The response surface methodology (RSM) was applied to minimize the number of runs and investigate the optimum operating conditions. Thirty runs were carried out and the optimum conditions for COD and color removal were statistically obtained 95.80% and 96.36% at H2O2/Fe2+ molar ratio 0.23, current density 79.20 mA, pH 4.61 and reaction time 14.72 min.