Pt-based catalysts are widely employed for hydrogenation reactions of industrial interest. In hydrogenation conditions H2 is activated by Pt nanoparticles and homolitically split to give Pt-hydrides and atomic hydrogen that then spills on the support. Several types of Pt-hydrides may be formed and the Pt-H frequencies are sensitive indicators of their nature. We would investigate the interaction/reaction of H2 with highly dispersed Pt nanoparticles supported on Al2O3 and C supports with Inelastic Neutron Scattering. It will allow to monitor the vibrations of H-containing species and so to follow simultaneously the changes occurring on the metal and on the support in the presence of H2. The collected data will be compared with those already obtained by in situ FT-IR spectroscopy. The unprecedented sensitivity of LAGRANGE spectrometer together with its optimal resolution will give access to spectroscopic details previously not accessible and it will help shading more light on the PtH phases formed, on their stability and on the support sites where hydrogen spills in different conditions, i.e. metal dispersion, support type, hydrogen content and activation temperature.