Using Camellia oleifera shell as starting material, production of activated carbon rich in mesoporous structure has been investigated with water vapor gasification followed by phosphoric acid modification. This method is found to be very effective in increasing the mesoporous ratio of the activated carbon. The micropores of the activated carbon gasified by water vapor (raw activated carbon) serve as channels for phosphoric acid impregnation to enlarge the pore size. Results of the activated carbon modified by phosphoric acid (final activated carbon) show a high mesoporous ratio of 61%, which is twice as high as that of raw activated carbon. Such modification also increases the BET surface area and total pore volume to 1608 m(2)/g and 1.17 cm(3)/g, respectively. The final activated carbon exhibits high adsorption capacity for methylene blue and iodine, with the adsorption values of methylene blue and iodine increasing from 180 to 1012 mg/g to 330 and 1326 mg/g, respectively. The present preparation is a convenient yet promising method to combine gasification and modification to obtain activated carbon with highly developed mesoporous structures. (C) 2011 Elsevier Ltd. All rights reserved.