Nanocrystalline TiO2 powder with and without Fe3+ doping were successfully synthesized at low temperature by a microwave-assisted sol–gel method. The synthesized TiO2 powders were characterized by XRD, BET, FT-IR and SEM. It was found that anatase phase was formed after refluxed at 80°C using a domestic microwave oven. Antibacterial behavior towards E. coli was then studied under UV and fluorescent irradiation. The synthesized pure TiO2 powder exhibited superior antibacterial activity under fluorescent irradiation compared to the commercial TiO2 (Degussa P25). It can efficiently destroy E. coli bacteria after 20 min with UV irradiation and 3 h with fluorescent light; this good activity is mainly related to the high OH radicals on its surface. It was also observed that the synthesized powders have smaller crystallite size and larger specific surface area than those of Degussa P25 due to the absence of high temperature calcination requirement.