Palladium and gold modified TiO2 (Degussa P25) under the effect of feeding oxygen and ozone containing mixture to the reactor under UV-A and UV-C irradiation were examined for their catalytic activity in the reaction of adipic acid oxidation. The samples were synthesized by extractive-pyrolytic method by loading 0.5% of the active metal having particles size varying from 7 to 12 nm. The XRD, TEM and BET methods were employed for their structural and chemical characterization. In the presence of oxygen under UV-A light the apparent first-order reaction rates constants of Pd- and Au-modified TiO2 samples were respectively 1.7 and 2.3 times higher than that of the pure TiO2 under the same conditions. These higher reaction rate constants are due to the more efficient separation of the electron–hole charge carriers generated during irradiation. Further, the effectiveness of the catalysts in regard to the photooxidation of adipic acid in the presence of ozone is greater both under UV-C and UV-A light with all the tested samples. The reaction rate constants under monochromatic 254 nm irradiation are about 3 times higher than those evaluated with polychromatic (λmax=365 nm) light. This is due to the additional generation of HO• radicals by the ozone on the conduction band of the TiO2 photocatalysts as well as the result of O3 photolysis by the UV-C light photons of high energy.