Porous carbons with large surface areas and pore volumes, as well as relatively uniform micropore texture were prepared by CO2 activation of ordered porous carbon CMK-1 for hydrogen storage. Both activation temperature and time were studied. The structure and texture changes in the carbons were investigated by using XRD and nitrogen sorption. Under the optimum condition that treating with CO2 at 950 degrees C for 6 h, a high H-2 uptake of 2.19 wt% was obtained at 77 K and 1 bar. The capacity is almost twice that of CMK-1 and higher than that of the reported porous carbons synthesized by silica templates. The pores smaller than 1 nm were confirmed to be the most efficient for hydrogen sorption. Besides, high efficiency of surface areas (4.50 x 10(-6) mol/m(2)) and micropores (1.36 x 10(-2) mol/cm(3)) were got for the H-2 uptake at 77 K and 1 bar. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.