The feasibility of photocatalytic oxidation of nitrite using TiO2 supported on hollow glass microbeads as a photocatalyst by sunlight was studied. The results showed that 1.1 x 10(-4) mol/dm(3) of nitrite can be completely photocatalytically oxidized after 120-min illumination by sunlight. The conversion of nitrite was increased rapidly by adding a small amount of H2O2, Fe3+ and Pd2+. The effects of parameters such as the amount of TiO2/beads, air flow, initial pH, dichromate, SO42-, NO3-, Cl- and organic compounds on the photocatalytic oxidation of nitrite were also studied. The possible mechanisms of photocatalytic oxidation of nitrite were investigated. After 150-h illumination by sunlight, there was no significant loss of the photocatalytic activity of TiO2/beads. (C) 2002 Elsevier Science Ltd. All rights reserved.