Hydrogen spillover involves dissociation of molecular hydrogen at the surface of metals, particularly transition metals, followed by migration of the hydrogen atoms across the surface which in this case is few-layer graphene. Surface functionalisation, particularly oxygen functionalisation of graphene has been shown to increase this effect, but the mechanism is not known. In-situ, inelastic neutron scattering studies can distinguish between weakly bound hydrogen atoms, physically bound hydrogen molecules and chemically bound hydrogen atoms including differentiating hydrogen atoms that are in clusters of up to three hydrogen atoms in nearest-neighbour configuration. Using few-layer graphene¿s doped with platinum nanoparticles and exhibiting surface oxygen content ranging from 7-30 wt.%, we will study the spillover mechanism with the aim of elucidating the bound state of hydrogen atoms.