Photoelectrocatalytic (PEC) inactivation of Escherichia coli K-12 by cuprous oxide (Cu2O) film irradiated by visible light is firstly reported. A complete inactivation of about 7 log of E. coli was obtained for Cu2O film within 6 h. The bacterial inactivation efficiency was significantly improved in a photoelectrochemical cell, in which 7 log of E. coli could be completely inactivated within 2 h by Cu2O film with a 0.1 V bias. Electric charge transfer between electrodes and E. coli, and electric charge inactivation towards E. coli were investigated using membrane-separated reactor combined with short circuit photocurrent technique. H2O2, hole, and toxicity of Cu2O film were found responsible for the inactivation of E. coli. Toxicity of copper ions (including Cu2+ and Cu+) leakage from Cu2O films was determined and the results showed that the amount of leakage copper ions was not toxic to E. coli. Finally, the Cu2O film was proved to be effective and reusable for PC and PEC inactivation of E. coli. (C) 2014 Elsevier Ltd. All rights reserved.