An economy based on hydrogen as an energy carrier is one of the most promising solutions against the greenhouse effect problem, due to the large amount of energy produced by the reaction of H2 with O2 and the clean combustion, free from pollutants. In the wide panorama of hydrogen storage materials, carbon based nanostructures are rather attractive, thanks to the low weight and cost of carbon. In particular, the alkali cluster intercalated fullerides guarantee hydrogen storage performances, partly meeting the US Department of Energy (DOE) requirements for on-board applications.With this proposal, we seek to further investigate the mechanisms behind the absorption of hydrogen, exploiting the unique capability of µSR technique to study separately the atomic hydrogen chemisorption through the formation and the further reaction on muonium (Mu), a light isotope of hydrogen.