The reaction of metal chloride-GIC with ammonia has been examined from the kinetic, thermodynamic and structural points of view. This reaction, which is widely reversible between two values of the ammonia/metal chloride ratio, can be used for the chemical storage of thermal energy or cold generation. The reaction rates have been found to be larger than those of non graphitic metal chlorides. The diffraction studies show that the final compounds are inclusion compounds rather than GIC. This structure allows an easy transfer of the ammonia molecules between inside/outside graphite crystallites.