The wastewater obtained during the exploration of oil and gas is known as produced water (PW). It contains organic and inorganic pollutants that are generating problems for aquatic life and humans. For degradation of hazardous organic pollutants in PW, Fenton like oxidation experiments were conducted using nanoscale zerovalent iron (n-ZVI). For this study laboratory-scale batch reactor was performed. Experiments were carried out at room temperature and 200 rpm magnetic stirrer speed. Design-Expert software was used for the optimization of Fenton like oxidation process to obtain the maximum removal of COD under optimal values of independent variable such as n-ZVI dosage, pH and contact time. To obtain suitable experimental design, Box-Behnken design (BBD) based on response surface modelling (RSM) was applied. n-ZVI concentration, pH, and contact time were coded factors as A, B and C, respectively. At optimal values of variables such as; n-ZVI concentration 5.17 g/L, pH 2.80 and contact time 98.3 min., the maximum removal of COD was predicted as 61.7. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2021.