The efficiencies of TiO(2-)based bulk and supported catalysts in the NOx (NO + NO2) removal from flowing NO-O-2-N-2 mixture under UV irradiation are quantitatively assessed by measuring the outlet NO and NO2 concentrations as a function of irradiation time. It is found that specific photocatalytic activity of TiO2 in this process can be considerably enhanced by dispersing TiO2 over high-surface alumina or by incorporating into TiO2 alkaline additives (BaO, urea). Effect of platinum doping is dependent on the Pt oxidation state. The mechanism of NO photooxidation on TiO2 and the role of OH radicals and O-2-species in it are discussed. (C) 2011 Elsevier B.V. All rights reserved.