In this work pristine CuO, NiO and CuO/NiO-1 nanocomposite (NC's) and Triton X 100 (TX-100) added CuO/NiO-2 NC's was prepared by simple co-precipitation method. The synthesized samples was characterized using X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy with energy-dispersive X-ray (EDX) analysis, X-ray Photoelectron Spectroscopy (XPS), Fourier transform-infrared spectroscopy (FTIR), Raman spectroscopy, UV–visible spectroscopy (UV–vis) and photoluminescence (PL). The CuO, NiO, and CuO/NiO-1 sample crystallite size was found to be 73.23 nm, 35.52 nm and 32.57 nm, respectively, while the reduction of crystallite size to 17.24 nm in CuO/NiO-2 resulted in a decrease of the CuO/NiO-2 bandgap value to (Eg) = 1.38 eV. The refractive index (n) values for prepared CuO, NiO, CuO/NiO-1 and CuO/NiO-2 samples are 2.56, 2.35, 3.23 and 3.25, respectively. Furthermore, the other optical parameter values extinction coefficient (k) and Real (εr) and imaginary (εr) dielectric constants are investigated. The CuO/NiO-2 sample have higher photocatalytic degradation percentage (99%) with velocity constant, kobs = 7.25035 ± 0.00987 × 10−4 min−1 compared with other CuO (80%), NiO (81%) and CuO/NiO-1 (92%) against Methylene blue (MB). © 2024 Elsevier GmbH