Nanoparticles of copper oxide (CuO) were achieved via thermal treatment for Cu(II) organometallic complex at calcination temperature up to 650°C. CuO nanoparticles that synthesized were elucidated by different spectroscopic techniques such as X-ray diffraction, energy-dispersive X-ray spectroscopy. CuO nanoparticles were accepted by scanning electron microscopy analysis as its average diameter was from 15 to 20 nm nanoparticles, and N2 adsorption–desorption as the Brunauer–Emmett–Teller surface area was originated to be 42.674 m²g^–1. Studying the adsorption of acid red 57 (AR57) onto CuO nanoparticles from aqueous, to evaluate the influence of pH, initial dye concentration, dosage, temperature, and contact time. Practical results clarified that the adsorption potential of CuO for AR57 was improved in acidic instead of basic solutions. The kinetics and equilibrium adsorption data were analyzed using the common adsorption models. These outcomes detect that Langmuir isotherm fits with the practical data obtained by a good level. The dye uptake process followed the pseudo-second-order rate expression. The activation energy of adsorption was also evaluated and found to be 30.94 kJ/mol, indicating that the adsorption is chemisorption. Various thermodynamic limits, such as ΔG, ΔH, and ΔS were determined at various temperatures using adsorption equilibrium constants obtained from the Langmuir isotherm. Thermodynamics of adsorption detect the endothermic and spontaneous nature of such process.