BACKGROUND In recent decades, rapid population growth and industrial development have led to the release of toxic compounds into water resources. Several technologies have been proposed to address the problem, and among them, the 3D electro-Fenton process has found great popularity due to its high efficiency and simple operation. In the 3D electro-Fenton process, the type of particle electrode is one of the most important factors owing to its impact on the reduction of energy consumption and generation of reactive species. In the present study, the optimization of the 3D electro-Fenton process coupled with iron-coated nickel foam (NF-Fe), as a new particle electrode, in the removal of acid orange 10 was investigated using response surface methodology (RSM). RESULTS The RSM results showed that the quadratic model has a high R-2 and high F-value based on ANOVA analysis. The optimum efficiency of dye removal (99.15%) was obtained at pH 5.6, an NF-Fe dosage of 0.68 g L-1, a time of 34.6 min, and current density of 23.62 mA cm(-2). Comparative tests showed the high efficiency of the 3D electro-Fenton process compared to other electrochemical systems. Quenching experiments demonstrated the production of different reactive species in the 3D process. The stability experiment proved that the NF-Fe has a high potential to improve the long-term degradation of dye. CONCLUSIONS Due to its high efficiency, production of more reactive species and excellent stability of the NF-Fe electrode, this 3D electro-Fenton process is an excellent option for removal of dye from aqueous solutions. (c) 2019 Society of Chemical Industry