Based on the first-principles density functional theory, we proposed a stable icosahedral B-12-containing core-shell structure of B-12@Mg20Al12. The vibrational frequency analysis and the molecular dynamics (MD) simulations indicate the good stability of B-12@Mg20Al12 structure. Analysis of the chemical bonding characters shows that there are multi-center two-electron a bonds formed by p electrons of B and Al atoms and s electrons of Mg atoms, which can form strong connections in the whole B-12@Mg20Al12. This can be the powerful evidence of the structural stability. The potential application of B-12@Mg20Al12 in hydrogen storage has also been investigated. Calculation results show that about 146 hydrogen molecules, which present a double-shell distribution, can be absorbed at most, corresponding to a high hydrogen capacity of 23.7 wt%, which means the B-12@Mg20Al12 can be a promising candidate of high-capacity hydrogen storage materials. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.