In this experiment MgH_2 impregnated into active carbon will be investigated through IINS. Since it is known that the enthalpy of formation of a material is lowered by increasing its surface energy, it is possible to attain hydride destabilisation by decreasing the particle size, reaching a lower H_2-release temperature. In general, particles having nanoscale size are characterised by a different thermodynamics, a faster kinetics, and an increased number of defects. However, although preparation methods are being developed to infiltrate or impregnate hydrides into nanoporous carbon, the physical properties of such nanodispersed hydrides are still little known. We are convinced that neutron spectroscopy will clarify some crucial aspects of these new advanced materials. IINS data from TOSCA on NaAlH_4 infiltrated into active carbon have already revealed a totally modified lattice dynamics.