The recent discovery of superconductivity in Ca-intercalated graphite (C6Ca) has refocused considerable interest onto graphite intercalated compounds (GICs). We would like to study the hydrogen chemisorption mechanism and the solid state properties of the C6Ca ternary systems using in-situ neutron diffraction. Our preliminary adsorption results show that the hydrogen can chemisorb in C6Ca at elevated temperatures well in excess of the composition expected due to the simple formation of CaH2 after the reaction. Furthermore, the resultant materials still shows superconductivity with a slightly depressed Tc, implying hydrogen uptake into the galleries and concomitant layer expansion. In this proposal we would like to follow the intercalation and structural staging transitions of this new material, exploiting the unique ability of neutron diffraction to locate the protons.