In this study, oak fruit as a biomass was used to prepare CuO/OBM nanocomposite and the electrochemical hydrogen storage (EHS) capacity of this nanocomposite was investigated. The product was characterized via energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), Brunauer-Emmett-Teller (BET), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Then, the effect of CuO/OBM ratio on the electrochemical hydrogen storage was investigated via chronopotentiometry method. After 20 cycles, the discharge capacities of OBM and CuO/OBM nanocomposite under 1 mA current were achieved from 3490 to 5950 mAh/g, respectively. Results show that coating of CuO on the OBM leads to improve the discharge capacity, but by increasing the CuO/OBM ratio, the discharge capacity has been decreased. Results of this study show that produced nanocomposite can be hopeful in replacing of fossil fuel. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.