According to recent theoretical studies, carbon nanostructures decorated with light transition metals could provide a route towards room temperature reversible hydrogen storage, a major roadblock for fuel-cell powered vehicles. Vibrational spectroscopies are the ideal experimental techniques to confirm the recent predictions of a metal-hydrogen bond of about 0.5 eV per H-2 molecule, which is expected to enable H-2 desorption at moderate temperatures. Here, we report first-principles results of the vibrational spectrum of representative systems, namely, TiHn complexes adsorbed on fullerenes. The obtained distinctive features should be found in a successful experimental realization of these materials. (C) 2007 Elsevier B.V. All rights reserved.