Hydrogen storage on multiwalled nanotubes (MWNTs) was dependent on the degree of catalyst removal. At atmospheric pressure, removal of the catalyst decreased the uptake from 0.6% to below detection limits. Hydrogen uptake of the metal oxide catalyst ranged from 0.25 to 0.98%, depending on surface area. Normalization by metal content and temperature-programmed desorption studies suggest hydrogen dissociation and subsequent spillover to the MWNT. Metal-support interactions were key to the spillover; dry mixing of the MWNT and catalyst did not enhance storage, whereas in situ production increased storage by 40%. The moderate temperature range of this material suggests a novel material for hydrogen storage applications.