Formation of alkaline-earth metal amidoboranes M(NH₂BH₃)₂(M = Be, Mg, Ca, Sr, Ba) and unimolecular dehydrogenation reactions were computationally studied at the B3LYP/def2-TZVPPD level of theory. Formation of M(NH₂BH₃)₂from ammonia borane and MH₂is exergonic, but subsequent unimolecular dehydrogenation reactions are endergonic at room temperature. In contrast to alkali metal amidoboranes, for M(NH₂BH₃)₂the nature of M significantly affects their reactivity. Activation energies for the dehydrogenation of first and second hydrogen molecules decrease from Be to Ba. In case of Be compounds, intramolecular M···H–B contacts play an important role, whereas for heavier analogs such contacts are much less pronounced.