In this paper, the efficiency of Iron-Hexacyanoferrate (FeHCF) and Copper-Hexacyanoferrate (CuHCF) as the cathode materials for using in the energy storage application have been investigated using Density Functional Theory. The changes of their lattice parameters due to the insertion of K+ cation were explored. It was found that these changes for CuHCF are less than FeHCF. FeHCF, KFHCF, CuHCF, KCuHCF, and K2CuHCF are found to have a half-metallic nature. In contrast, K2FeHCF is found to be a diamagnetic insulator. K+ diffusion through the FeHCF and CuHCF frameworks have the energy barrier of 1.46 eV and 1.00 eV, respectively. (C) 2017 Published by Elsevier B.V.