A novel eutectic hydrogen storage system, LiBH₄·NH₃–nNH₃BH₃, which exists in a liquid state at room temperature, was synthesized through a simple mixing of LiBH₄·NH₃ and NH₃BH₃ (AB). In the temperature range of 90–110 °C, the eutectic system showed significantly improved dehydrogenation properties compared to the neat AB and LiBH₄·NH₃ alone. For example, in the case of the LiBH₄·NH₃/AB with a mole ratio of 1 : 3, over 8 wt.% hydrogen could be released at 90 °C within 4 h, while only 5 wt.% hydrogen released from the neat AB at the same conditions. Through a series of experiments it has been demonstrated that the hydrogen release of the new system is resulted from an interaction of AB and the NH₃ group in the LiBH₄·NH₃, in which LiBH₄ works as a carrier of ammonia and plays a crucial role in promoting the interaction between the NH₃ group and AB. The enhanced dehydrogenation of LiBH₄·NH₃/AB may result from the polar liquid state reaction environments and the initially promoted formation of the diammoniate of diborane, which will facilitate the B–H⋯H–N interaction between LiBH₄·NH₃ and AB. Kinetics analysis revealed that the rate-controlling steps of the dehydrogenation process are three-dimensional diffusion of hydrogen at temperatures ranging from 90 to 110 °C.