The catalytic performance of LaCuO3 in photo Fenton-like oxidation of the food dye, Tartrazine was tested under visible and IN light irradiation. The influence of the initial pH, the initial hydrogen peroxide concentration ([H2O2)(o)), the catalyst loading and the source of light irradiation on Tartrazine degradation and decolorization were investigated sequentially. The initial Tartrazine concentration was kept constant at 100 ppm and the experiments were carried out for 120 min (the first 30 min in darkness and the next 90 min under visible or UV light irradiation). The optimum reaction conditions were determined as 50 degrees C of reaction temperature, 3 of pH, 8 mM of [H2O2](o), and 0.25 g/L of catalyst loading. Under the optimum conditions 46.6% degradation and 83.9% decolorization efficiencies were achieved under visible light irradiation whereas 64.4% degradation and 90.2% decolorization were accomplished under UV light irradiation. At the end of 120 min the copper leaching was determined to be 0.56 and 0.6 ppm under visible and UV light irradiation, respectively, and the toxicity were evaluated as 5.9% in terms of Lepidium satiuum root growth inhibition under the optimum reaction conditions. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.