The photocatalytic degradation of dyes was studied using nano titania–zirconia composite catalyst from textile wastewater. The composite photocatalysts were prepared by sol–gel method and were characterized by X-ray diffraction, transmission electron microscopy and BET analyzer. The textile effluent was characterized by various analytical procedures before treatment. The effects of initial pH of the solution, effluent concentration, catalyst concentration and air flow rate on the degradation of pollutants were investigated on the basis of chemical oxygen demand. The Langmuir–Hinshelwood based model was validated with the experimental data based on reactive red 120 removals.