The treatment of methyl parathion (MP) aqueous solution with the application of Fenton oxidation using catalyst (Fe2+) was investigated under batch mode of operation. The aims of this study are to evaluate the COD removal and removal efficiency of MP from aqueous solution by Fenton reagent and investigate the role of different parameters such as concentration of initial pH, Fe2+ dosage, H2O2 dosage, initial concentration of MP, temperature, and reaction time. The initial COD value was 440 mg/L for MP concentration of 11.4 × 10−5 M. It was observed that removal was faster at acidic pH and maximum COD and MP removal were 64.54 and 74%, respectively, at pH value 3. When vary the doses of H2O2, maximum COD and MP removal of 79 and 92%, respectively, were achieved at H2O2 concentration of 6.53 × 10−1 M, Fe2+ concentration 8.99 × 10−3 M and pH 3. Regarding degradation kinetics of MP, Behnajady–Modirshahla–Ghanbery model showed high correlation coefficient (R2) as compared with first‐order and second‐order models at different operating conditions using Fenton oxidation. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 420–427, 2017