CuO/ZnO/MgO nanocomposites with various amounts of copper oxide (CuO = 0, 0.5, 1 and 2 mol) were fabricated by utilizing the separated white egg and auto-combustion method. The as-fabricated composites were heat treatment at 300 °C and 500 °C for a half-hour, separately. The calcined nanocomposites were examined utilizing various techniques such as X-ray diffraction (XRD), High-Resolution transmission electron microscopy (HR-TEM), Field emission scanning electron microscopy (FE-SEM), Diffuse reflectance spectroscopy (DRS), Fourier Transform Infrared Spectroscopy (FTIR) and UV–Visible spectrophotometer. The surface characteristics of the calcined CuO/ZnO/MgO nanocomposite were estimated employing the Brunauer Emmett Teller method (BET). Photocatalytic activities of the previous nanocomposites were investigated through the decomposition process of reactive red 195 dye with …