Solid state electrolytes are key components for all solid state battery to deal with the safety concern. Development of new solid electrolytes necessitates fundamental understanding of structure-ion transport correlation in addition to their potential application. We propose here to investigate detailed mechanistic insight into Li+ ion diffusion in a new class of lithium ion conductor based on bimetallic borohydride halides (LiCe(BH4)3X; X = Cl, Br) (conductivity; ~10-4 S cm-1 at 298 K, EChem window: 7V) by using muSR. The present study will investigate influence of halide substitution on the lithium diffusion of LiCe(BH4)3X; X = Cl, Br for the first time ever reported in literature. The muSR technique will be utilised to probe lithium diffusion pathways and to investigate temperature dependent behaviour of diffusion coefficient of the newly proposed conductors.