The photosterilization of Escherichia coli cells using iron-doped TiO2 (Fe/TO) particles was investigated under the conditions of initial cell concentration of 1 x 10(11) cells/m(3), incident light intensity of 14 W/m(2) and Fe/TO concentration of 0.01 kg/m(3). Among the Fe/TO particles prepared by changing the Fe weight fraction (W-Fe/TO = 0-3.0 wt%) and calcination temperature (T-c = 473-1073 K), it was found that the highest sterilization rate was achieved at a dissolved oxygen (DO) concentration of 0.54 ppm when using the Fe/TO particles prepared at W-Fe/TO = 1.8 wt% and T-c = 773 K. In the photosterilization using the selected Fe/TO particles under various DO concentrations of 0.54-7.9 ppm, the sterilization rate of the cells increased with increasing DO concentration up to 2.0 ppm and the rate was nearly constant above this DO concentration. At lower DO concentrations of 0.54-2.0 ppm, furthermore, the rate constant in the photosterilization with the Fe/TO particles was 1.5-13 times higher over the virgin TiO2 without iron doping.