The aim of this proposal is to use neutron powder diffraction to characterise a series of 9 new halide modified lithium amides and imides which are of interest as reversible hydrogen storage materials. The crystal structure of these phases will be determined, including the precise location of the lithium and deuterium positions. The structural relationships among this family of new phases will be determined in order to understand and optimise their hydrogen storage properties. These new materials have been shown to exhibit improved de/absorption properties, which have been linked to lithium ion conductivity. We will use Fourier mapping to gain an insight into lithium ion diffusion pathways at elevated temperature for selected phases and develop a deeper understanding of the mechanism of hydrogen storage in these systems to inform the design of next generation hydrogen storage materials.