The study of the heterogeneous photocatalytic oxidation of phenoxyacetic acid in presence of near-UV illuminated TiO2 is carried out. The Langmuir-Hinshelwood kinetics model fits the experimental data of phenoxyacetic disappearance, and reaction rate and equilibrium adsorption constants are reported. The effect of temperature, pH, intensity of incident light and mass of catalyst on the reaction rate is ascertained. Some intermediate products are detected and carbon dioxide was found to be the final product of the reaction.