The feasibility of photocatalytic oxidation of NO2- ions using TiO2 beads as a photocatalyst was studied. The results show that 400 mL of 1.1x10(-4) mol/L of NO2- ions can be completely photocatalytically oxidized after 25-min illumination by a 375 W medium pressure mercury lamp. The photocatalytic oxidation efficiencies of the NO2- ion were increased rapidly by adding a small amount of H2O2 or Fe3+, and the effects of parameters such as the amount of TiO2 beads, air flow and initial pH on the photocatalytic oxidation of the NO2- ion were also investigated. After 120-h illumination, there was no significant loss of photocatalytic activity of the TiO2 beads. The feasibility of photocatalytic oxidation of NO2- ions using solar energy as a light source was also studied. As the density of the TiO2 beads prepared was lower than 1.0 g/cm(3), they can float on the water surface and be easily separated from water.