Hydrogen storage in carbon nanofibers (CNFs) prepared by the floating catalyst method is investigated. The pristine CNF materials are subjected to several heat treatments under different temperatures with the protection of Ar for 2 h to get favorable structure and adsorption surface. These treatments improved the graphitization degree and surface activity of the CNFs effectively. At last these materials can absorb similar to4 wt.% of hydrogen at room temperature under similar to10 MPa. The effect of the surface functional groups on the adsorption performance of the CNFs is highlighted. (C) 2002 Elsevier Science B.V. All rights reserved.