Nanocrystalline copper oxide (CuO) powder was synthesized through solid-state co-precipitation technique using copper sulfate pentahydrate and sodium hydroxide pellets as a source materials. Crystalline nature and surface morphology of the sample are studied through x-ray diffraction, field emission scanning electron microscopy, energy dispersive x-ray, and Fourier transform infrared spectroscopy. Optical properties of synthesized CuO nanopowder were investigated by UV–Vis absorption and photoluminescence spectroscopy. X-ray diffraction study reveals that CuO nanoparticles are in monoclinic structure and crystalline size is found to be around 15 nm as estimated from Debye-Scherrer formula. FESEM measurement confirms that the particles are in almost irregular shape, and some nanorod-like structures are noticed. FTIR spectrum confirms the formation of high-quality and pure CuO nanoparticles. The effect of various solvents on optical properties of CuO nanoparticles is studied. From UV–Vis absorption measurement, a strong quantization along with varying band edges in different solvents was observed. It is seen from photoluminescence spectra that the intensity of emission as well as emission peak wavelength changes with solvents.