The treatment of industrial wastewater is one of the most important problems to be considered today. In recent years, advanced oxidation processes based on the production of hydroxyl radicals with high oxidation potential are preferred in the treatment of wastewaters. In this study, color and chemical oxygen demand (COD) removal efficiencies of sunflower oil industrial wastewater have been investigated by applying a heterogeneous Fenton process. Fe(III)/MnO2 and Fe(III)/SnO2 catalysts have been prepared by the co-precipitation method and characterized by scanning electron microscopy and Brunauer-Emmet-Teller techniques. The effects of the amount of the catalyst, pH, hydrogen peroxide concentration, temperature, reaction time and mixing speed on the process have been studied and the optimum conditions have been determined. In the heterogeneous Fenton process, 98% color and 89% COD removal efficiency for Fe(III)/MnO2 catalyst and 92% color and 67% COD removal efficiency for Fe(III)/SnO2 catalyst have been obtained. This result indicates that Fe(III)/MnO2 catalyst is more effective in the treatment of sunflower oil industrial wastewater. The stability and reuse of the catalysts have also been tested. These catalysts successfully overcome the two problems encountered during the heterogeneous Fenton process. They are reusable and there has been no significant reduction in the efficiency of the catalysts even after four consecutive runs.