The hydrogen adsorption capacity of various carbon structures including activated carbon (AC) and carbon nanofibers (CNFs) has been measured as a function of pressure and temperature. Results have shown the correlation between hydrogen storage capacity and specific micropore surface area and also explain the hysteresis in H-2 uptake observed at 273 and 299 K principally with CNFs materials. The highest H-2 storage value (2.02 wt%) was obtained with AC at 10 bar and 77 K. (C) 2009 Elsevier B. V. All rights reserved.