Boron-substituted graphene decorated with potassium metal atoms was considered as a novel material for hydrogen storage. Density functional theory calculations were used to model key properties of the material, such as geometry, hydrogen packing, and hydrogen adsorption energy. We found that the new material has extremely high hydrogen storage capacity: 22.5wt%. It is explained by high-density packing of hydrogen molecules into hydrogen layers with specific geometry. In turn, such geometry is determined by the composition and topology of the material. Copyright (c) 2014 John Wiley & Sons, Ltd.