The structural stability and hydrogen release properties of M-doped KMgH3 (M = Li, Na, Rb, or Cs) were examined using density functional theory (DFT) calculations. The reaction enthalpies (Delta M) of the four possible dehydrogenation reaction pathways were calculated using the doped structures with different phases (Pm (3) over barm, Pnma, and R3c). The most favorable reaction pathway among these four pathways was found. Among the dopants investigated, the most promising dopant for this reaction was Li. In addition, the application of pressure was found to be useful for tuning the reaction enthalpies of the dehydrogenation reactions. Overall, the results present an efficient means of designing new promising perovskite-type hydrides for hydrogen storage. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.