The high-pressure H(2) sorption isotherms of polyaniline-vanadium pentoxide nano-composites (PANI-VONC) have been performed at liquid nitrogen temperature. A large increment of hydrogen storage capacity occurs in PANI-VONC (similar to 1.8 wt%) in contrast to that in pristine vanadium pentoxide (similar to 0.2 wt%) and in non-treated polyaniline (similar to 0.2 wt%). it is considered that the reason for the enhancement of hydrogen storage in PANI-VONC is the intercalation of polyaniline (PANI) into the vanadium pentoxide layers. The intercalation of PANI decreases the interlayer distance from 1.1 nm between vanadium pentoxide layers to 0.72 nm between vanadium pentoxide layer and polyaniline layer. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.