The present work explores the impact of electro coagulation (EC) method on the treatment of waste from rice mill industries using two different electrode materials (Iron (Fe) and Aluminum (Al)). The influence of different parameters such as inter-electrode distance (4–7 cm), effluent pH (6–8), current density (10–30 mA/cm2) and treatment time (20–40 min) on the reduction of chemical oxygen demand (COD), total dissolved solids (TDS) and total soluble solids (TSS) of rice mill effluent (RME) was evaluated through batch experimental runs using Box-Behnken design. Results reveal that the percentage removal of COD, TDS and TSS increased up to an inter-electrode distance of 6 cm, pH of 7, current density of 20 mA/cm2 and treatment time of 30 min and then decreased for both electrodes. In addition, mathematical models were developed for both electrodes in order to predict the experimental data. A numerical optimization method was applied to find out the optimal operating parameters to treat RME, and the percentage removal of COD, TDS and TSS was found to be 94.79, 96.62 and 88.76 %, using the Al electrode, as well as 76.63, 78.51 and 72.03 %, for the Fe electrode, respectively. The comparison of the results attained demonstrate that the Al electrode is more suitable to treat RME than Fe using EC method