Oxidation by Fenton-like reactions is proven and economically feasible process for destruction of a variety of hazardous pollutants in wastewater. We report herein the oxidation of methylene blue, a basic dye of thiazine series using a Fenton-like reaction at normal laboratory temperature and at atmospheric pressure. The effects of different parameters like the initial concentrations of dye, Fe2+, and H2O2, pH of the solution, reaction temperature, and added electrolytes on the oxidation of the dye present in dilute aqueous solution in the concentration range (3.13-9.39) × 10-5mol dm-3 (10-30mg l-1) have been assessed. The results indicate that the dye can be most effectively oxidized in aqueous solution at dye:Fe2+:H2O2 molar ratio of 1:1.15:14.1. More than 98% removal of the dye could be achieved in 1 h in the pH range 2.2-2.6 at 299 K which corresponds to about 81% reduction of the initial COD. The results will be useful for designing the treatment systems of various dye-containing wastewaters. © 2001 Elsevier Science B.V.