The photocatalytic degradation of TNT in a circular photocatalytic reactor, using a UV lamp as a light source and TiO 2 as a photocatalyst, was investigated. The effects of various parameters such as the initial TNT concentration, and the initial pH on the TNT degradation rate of TiO 2 photocatalysis were examined. In the presence of both UV light illumination and TiO 2 catalyst, TNT was more effectively degraded than with either UV or TiO 2 alone. The reaction rate was found to obey pseudo first-order kinetics represented by the Langmuir-Hinshelwood model. In the mineralization study, TNT (30 mg/l) photocatalytic degradation resulted in an approximately 80% TOC decrease after 150 min, and 10% of acetate and 57% of formate were produced as the organic intermediates, and were further degraded. NO - 3 NO - 2 , and NH + 4 were detected as the nitrogen byproducts from photocatalysis and photolysis, and more than 50% of the total nitrogen was converted mainly to NO - 3 in the photocatalysis. However, NO - 3 did not adsorbed on the TiO 2 surface. TNT showed higher photocatalytic degradation efficiency at neutral and basic pH.