This study investigated the process of potassium permanganate (KMnO4) oxidation and in situ formed hydrous manganese dioxides (delta MnO2) (i.e., KMnO4 oxidation and delta MnO2 adsorption) for the treatment of dye wastewater. The effectiveness of decolorization, removing dissolved organic carbon (DOC), and increasing biodegradable oxygen demand (BOD) were compared among these processes of KMnO4 oxidation, delta MnO2 adsorption, and KMnO4 oxidation and delta MnO2 adsorption. delta MnO2 adsorption contributed to the maximum DOC removal of 65.0%, but exhibited limited capabilities of decolorizing and increasing biodegradability. KMnO4 oxidation alone at pH 0.5 showed satisfactory decrease of UV-vis absorption peaks, and the maximum BOD5/DOC value of 1.67 was achieved. Unfortunately, the DOC removal was as low as 27.4%. Additionally, the great amount of acid for pH adjustment and the much too low pH levels limited its application in practice. KMnO4 oxidation and delta MnO2 adsorption at pH 2.0 was the best strategy prior to biological process, in balancing the objectives of decolorization, DOC removal, and BOD increase. The optimum ratio of KMnO4 dosage to X-GRL concentration (RKMnO4/X-GRL was determined to be 2.5, at which KMnO4 oxidation and delta MnO2 adsorption contributed to the maximal DOC removal of 53.4%. Additionally, the optimum pH for X-GRL treatment was observed to be near 3.0. (C) 2009 Elsevier B.V. All rights reserved.