Quasielastic neutron scattering (QENS) measurements together with equilibrium molecular dynamic (EMD) simulations have been performed to investigate the surface interaction between hydrogen molecules and a carbon material commonly used in polymer electrolyte membrane fuel cells (PEMFC), called XC-72. Half a monolayer of molecular hydrogen was adsorbed on to the carbon material at 2 K. QENS spectra were recorded at the time-of-flight spectrometer IN5 at 40, 45, 50, 60, 70, 80, and 90 K. Simultaneously the pressure was measured as a function of time to monitor the equilibrium surface coverage at each temperature. By using the Chudley and Elliott model for jump diffusion we found the diffusion coefficient at each temperature. At 350 K, a typical fuel cell temperature, the temperature function was extrapolated to a self-diffusion coefficient of 2.3 × 10-7 m2/s. We simulated graphite in contact with hydrogen molecules using EMD simulation. We simulated the system at different temperatures from 70 to 350 K in 20 deg intervals and for five numbers of H2 molecules NH2 ) 50, 100, 150, 200, and 300. The graphite was made of 9 sheets of graphene in a sandwich. The surface self-diffusion was found from the mean-square displacement, and the values from EMD simulations are the same order of magnitude as the experimental values at 90 K, but systematically higher, probably due to the ideal surface. From EMD simulation, we also calculated the average time between adsorption and desorption events on the surface. This was used to find the mean displacement of the hydrogen molecules between adsorption and desorption. This result showed that H2 molecules can move 80 Å at ambient temperatures and pressures, along the surface. Using these data, we conclude that catalyst support material in PEMFC contributes to the transport of reactant.