The uncapped and capped CuO nanoparticles were synthesized by solâ€“gel technique. Triethanolamine (TEA) was used as a capping agent to control the size and morphology of the CuO nanoparticles. The control of nanostructure and hence the optical properties of CuO nanoparticles are consciously achieved by using capping agent. The obtained samples were characterized by means of UVâ€“Visible spectroscopy (UVâ€“Vis), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FE-SEM) along with energy dispersive X-ray spectroscopy (EDS). UVâ€“Visible technique was used to measure the band gap of the synthesized samples. The XRD spectra of the synthesized samples confirmed the CuO nanoparticles with monoclinic structure. Antioxidant of CuO nanoparticles evaluated to L-ascorbic acid and BHA were used as standards. The antioxidant capacity was expressed as ascorbic acid comparable. Investigate of cyclic voltammetry applications examine of uncapped and TEA capped CuO nanoparticles.