The decoration of a BC 3 monolayer with the polylithiated molecules CLi4 and OLi2 has been extensively investigated to study the hydrogen-storage efficiency of the materials by first principles electronic structure calculations. The binding energies of both lithiated species with the BC3 substrate are much higher than their respective cohesive energies, which confirms the stability of the doped systems. A significant positive charge on the Li atom in each of the dopants facilitates the adsorption of multiple H2 molecules under the influence of electrostatic and van der Waals interactions. We observe a high H2-storage capacity of 11.88 and 8.70 wt% for the BC 3-CLi4 and BC3-OLi2 systems, respectively, making them promising candidates as efficient energy-storage systems. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.