Zinc oxide nanoparticles and cellulose acetate composite have been synthesized using the in-situ co-precipitation technique and characterized using Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analyses. The nanocomposite has been used as the adsorbent for the removal of Orange II dye from aqueous solution through adsorptive mechanism. The effect of concentration, pH, time contact, adsorbent dosage and temperature are investigated, and maximum percentage removal of the dye is calculated to be 83%. The Langmuir and Freundlich isotherm model gave a positive result with the adsorption experimental data with value of b and n equal to 0.075 and 1.197 respectively while regression coefficient R-2 equal to 0.839 and 0.859 in each case. The thermodynamics studies of the adsorption show that the adsorption reaction is exothermic and the process follows a pseudo second order kinetic model.