The interaction between KH and Mg(NH2)2 is investigated. Results from temperature-programmed desorption measurements on samples of [Mg(NH2)2][KH]x (x=0.5, 1.0, and 2.0) indicated that dehydrogenation from [Mg(NH2)2][KH] occurred through a two-step reaction with an onset temperature as low as 60 °C. Accompanied by hydrogen release, K2Mg(NH2)4 and MgNH successively developed at lower temperatures, whereas KMg(NH)(NH2) developed at higher temperatures. However, when dehydrogenation was conducted under isothermal and near-equilibrium conditions, a single-step reaction that led to the formation of KMg(NH)(NH2) was observed. KMg(NH)(NH2) is a new amide–imide complex. The synthesis of KMg(NH)(NH2) can be achieved either by dehydrogenation of the [Mg(NH2)2][KH] mixture or by thermal decomposition of the [K2Mg(NH2)4][Mg(NH2)2] mixture.