Pure CuO and Zn-doped CuO nanoparticles were synthesized from sol–gel process by reacting copper acetate monohydrate with a urea in distilled water at 80°C. The synthesized Samples were different concentrations but same annealing temperature at 400°C. The obtained samples were characterized by means of UV–visible spectroscopy (UV–vis), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Field emission scanning electron microscopy (FE-SEM) and Energy dispersive X-ray spectroscopy (EDS). UV–visible technique used to measure the band gap of the synthesized samples. The XRD spectra of the synthesized samples confirmed the CuO nanoparticles with monoclinic structure. All the functional groups of the pure and doped synthesized samples were investigated by FT-IR analysis. The morphological and elemental estimation of the pure and Zn-doped synthesized samples were examined by FE-SEM with EDS.