The monoammoniate of lithium amidoborane, Li(NH3)NH2BH3, was synthesized by treatment of LiNH2BH3with ammonia at room temperature. This compound exists in the amorphous state at room temperature, but at −20 °C crystallizes in the orthorhombic space group Pbcawith lattice parameters of a=9.711(4), b=8.7027(5), c=7.1999(1) Å, and V=608.51 Å3. The thermal decomposition behavior of this compound under argon and under ammonia was investigated. Through a series of experiments we have demonstrated that Li(NH3)NH2BH3is able to absorb/desorb ammonia reversibly at room temperature. In the temperature range of 40–70 °C, this compound showed favorable dehydrogenation characteristics. Specifically, under ammonia this material was able to release 3.0 equiv hydrogen (11.18 wt %) rapidly at 60 °C, which represents a significant advantage over LiNH2BH3. It has been found that the formation of the coordination bond between ammonia and Li+in LiNH2BH3plays a crucial role in promoting the combination of hydridic BH bonds and protic NH bonds, leading to dehydrogenation at low temperature.