Hydrogen storage on cation-decorated biphenylene carbon (BPC) and nitrogenated holey graphene (C2N) layered materials are addressed by dispersion-corrected density functional theory calculations. Maximum storage capacity and adsorption energy of a gas-phase H-2 monolayer adsorbed on both sides of (Li+, Na+, Mg2+, Ca2+)-doped layers are investigated. We find that cations distribute homogeneously on BPC and C2N with a maximum densities of 1.9 and 1.7 ion/nm(2), respectively. The H-2 adsorption on cation-decorated BPC shows binding energies that vary from -0.14 to -0.26 eV/H-2, depending on whether the cation is single or double charged, where the storage capacity are calculated to be around 10 wt%. Whereas, for cation-doped C2N, the H-2 binding energies vary from -0.11 to -0.31 eV/H-2, with storage capacity between 7.3 and 8.8 wt%. Our results suggest that cation-doped C2N is the most stable material, providing both reversibility and high capacity for hydrogen storage at operational conditions. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.