The textural structure and the surface property of activated carbon were selectively modified by KMnO4 oxidation. The activated carbon treated by KMnO4 oxidation in an acidic solution showed greatly enhanced H2O2 production by hydroxylamine oxidation clue to the creation of more surface quinoid species, and the yield of hydrogen peroxide approached 78% (0.66 wt.%). Structure and surface analyses revealed that KMnO4 oxidation in the acidic solution produced more phenolic but less carboxylic groups on the activated carbon, confirming the crucial role of the quinoid groups. It was further proposed that the quinoid groups serving as electron acceptors and redox mediators involved in the formation of H2O2 through a redox cycle. (C) 2010 Elsevier B.V. All rights reserved.