In this study, Density Functional Theory (DFT) calculations have been performed for BaYO3 perovskite with the generalized gradient approximation (GGA) as implemented in Vienna Ab-initio Simulation Package (VASP). The structural optimization of BaYO3 perovskite have been studied for the five possible phases: cubic, tetragonal, hexagonal, orthorhombic and rhombohedral to determine the most stable phase of BaYO3 perovskite. It has been found that the cubic phase is the most stable one and electronic and mechanical properties of this phase have been investigated. Moreover, the elastic anisotropy has been visualized in detail by plotting the directional dependence of compressibility, Poisson ratio, Young's and Shear moduli for cubic phase. Then, hydrogen bonding to BaYO3 perovskite has been conducted and hydrogen storage properties of BaYO3Hx (x = 3 and 9) such as: formation energy, cohesive energy and gravimetric hydrogen storage capacity have been analyzed. Having no study about BaYO3 perovskite and hydrogen bonding in the literature makes this study the first considerations of BaYO3 perovskite. Hence, this work could enlighten the possible future studies. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.