Practical hydrogen storage for mobile applications requires materials that contain large amounts of hydrogen, have low decomposition temperatures, and fast kinetics for absorption and desorption. Mixtures of two high-density hydrides such as LiBH4/MgH2, LiNH2/LiBH4, and LiNH2/MgH2 have recently emerged as an approach toward improved thermodynamic properties relative to their individual component reactions. However, in practice, appropriate thermodynamics is not enough to guarantee that hydrogen will evolve at the expected temperature and at a suitable purity and rate. We present a combined experimental/computational approach for a new, ternary combination of high density hydrogen storage materials, LiBH4/LiNH2/MgH2. Experimental data for these materials include kinetic desorption, powder X-ray, FT-IR, and MS and computational results are based on density functional theory calculations. We demonstrate reactions with improved hydrogen storage properties in terms of reversibility, kinetics, and hydrogen purity, while preserving high hydrogen density and favorable thermodynamics.