Herein, graphene nanocomposite of CuO–rGO is synthesized by simple precipitation reaction. Characterization by different techniques confirms the reduction of graphene oxide and formation of CuO–rGO. The CuO nanocrystals are uniformly distributed on graphene sheets. Neutron and X‐ray diffraction (XRD) prove the formation of single phase of CuO monoclinic crystal system with space group C2/c. Infrared spectroscopy shows vibration modes of graphene and CuO. Morphological characterization is carried out by scanning electron microscope (SEM) (SEM) and transmission electron microscope (TEM). It shows that the particle size ranges from 20 to 60 nm in which confirmed by four different theoretical approaches calculated from XRD peaks broadening data. The electronic properties using X‐ray photoelectron spectroscopy are also provided. The reduction of graphene oxide and formation of CuO–rGO nanocomposite is achieved and confirmed; the crystallite size and micro strain are calculated and tested with four different theoretical approaches based on X‐ray diffraction peaks broadening. X‐ray photoemission spectroscopy and fast fourier transform infrared spectroscopy prove the reduction of graphene by disappearance of graphene oxide peak and prove the ability of using in energy storage applications.