We ask for 3 days on EMU to study the Muon spectroscopy of both LiBH4 and Ca(BH4)2 as a function of temperature from 90K-650K. These materials have been extensively crystallographically investigated as prospective lightweight hydrogen stores. In both cases, direct hydrogen reversibility is only possible at elevated temperature and pressure. We believe this is a consequence of bulk Li+ mobility and disorder. While LiBD4 undergoes a superionic transition at 395K the (hydric) hydrogen remains attached to the BH4- unit which freely spins. We propose to study the ionic mobility (LiBH4), disorder (LiBH4 and Ca(BH4)2) and increased delocalisation of hydrogen (LiBH4 and Ca(BH4)2) as a function of temperature in these systems by Muon spectroscopy.