Nanostructured carbons are promising precursors for a high-capacity reversible hydrogen storage material with fast kinetics, but the interaction of H2 with pure graphite is too weak. We have made graphitic nanofibres (GNF) by electrospinning and have doped these with potassium, opening the intergraphene spaces to H2 and increasing the sorption enthalpy through charge transfer. Our recent work on bulk KC24(H2)x invoked quantum limitations on H2 capacity. For comparison, we wish to study structure and dynamics of H2 in K-doped GNF. By intercalating and then gradually hydrogenating K-GNF in situ on GEM at 55 K we will obtain time-resolved diffraction patterns unavailable using XRD, elucidating the intercalation process and hydrogen-induced lattice expansion to compare with INS data on the local H2 environment and our previous work.