NaAlH4 has been a model system for metal hydride hydrogen storage materials since the reaction was identified to be reversible. The decomposition pathway has been described by a number of in situ techniques including NMR, XRD and neutron diffraction. The dearth of high pressure attachments for in situ studies has inhibited the hydrogenation process to be measured. As a result, the pathway of hydrogenation has only been hypothesized by ex-situ XRD and NMR studies. Our recent in-situ 27Al and 23Na NMR spectroscopy studies at high pressure conclude that the postulated pathway was incorrect. The aim of this study is to confirm the findings from the in situ NMR data and develop a model detailing the pathway of hydrogenation. This data will be correlated with in situ synchrotron XRD data to precisely determine the deuterium positions as the reaction with deuterium takes place.