Coking wastewater contains high a concentration of refractory and toxic compounds to be treated before being discharged into the environment. The water quality usually cannot meet the discharge limits after conventional biological treatment processes. This article initially investigated the treatability of coking wastewater with conventional and modified Fenton processes for advanced treatment of coking wastewater. Based on the experimental results, up to 86% of chemical oxygen demand (COD) and 99.5% of phenol removals were achieved by the conventional Fenton process at original pH 7.8 within 60 min. pH adjustment was not performed due to the sudden drop in the original pH value, after the addition of Fenton's reagents. A modified Fenton process yielded comparable COD (82%) and phenol (98.5%) removals within 120 min at pH 3.0. The optimal operating conditions were determined as [Fe2+] = 300 mg/L, [H2O2] = 4000 mg/L, and pH = 7.8 for a conventional Fenton process, and [Fe0] = 300 mg/L, [H2O2] = 4500 mg/L, and pH = 3 for a modified Fenton process. © 2011 American Institute of Chemical Engineers Environ Prog, 32: 176-180, 2013