An antimony based luminescent organic-inorganic hybrid compound H3SbCl6(L)6 (1, L = 2-(3-methyl-1H-imidazol-3-ium-1-yl)acetate) has been prepared by the solvothermal method. It emits bright green light peaking at 525 nm, with an internal quantum yield (IQY) of 73% under 360 nm excitation. The negative thermal quenching (NTQ) effect has been observed in the temperature range of 77 K to 297 K. Due to its ionic structure, compound 1 is soluble in numerous organic solvents, including methanol, dimethyl sulfoxide (DMSO), etc. The solution processability combined with high quantum efficiency makes 1 a promising candidate as a luminescent coating material for optoelectronic devices.