The crystal structure of solvent-free Li2B12H12 has been determined by powder X-ray diffraction and confirmed by a combination of neutron vibrational spectroscopy and first-principles calculations. This compound is a possible intermediate in the dehydrogenation of LiBH4, and its structural characterization is crucial for understanding the decomposition and regeneration of LiBH4. Our results reveal that the structure of Li2B12H12 differs from other known alkali-metal (K, Rb, and Cs) derivatives.