We have recently discovered that light metal amides and imides are excellent cattalysts for the decomposition of ammonia. We request 3 days on POLARIS to perform in situ neutron diffraction measurements on lithium amide-imide (LiND2-Li2ND), while monitoring the ammonia decomposition reaction. Building on information obtained from our previous POLARIS experiment on this system, we will conduct a series of isotope exchange measurements which will help to develop an understanding of the catalytic reaction mechanism, a crucial step in optimising the reaction for use in on-demand hydrogen production applications.