The reduction of Cr(VI) by resting Escherichia coli cells was significantly enhanced by the quinone redox mediators, lawsone, menadione, anthraquinone-2-sulfonate and anthraquinone-2,6-disulfonate. In the presence of 0.2mM lawsone, over 97.5% Cr(VI) (100mgl −1 ) was reduced in 4h. The mediated reduction occurred at initial Cr(VI) concentrations of 50–250mgl −1 , and increased with increasing initial biomass concentrations from 0.05 to 1.2gl −1 . The addition of glucose as electron donor promoted the reduction process. Cu 2+ , Ni 2+ and Co 2+ inhibited, whereas Mn 2+ and Pb 2+ stimulated reduction. Four rounds of mediated reduction were completed in 19h, suggesting its stability and persistence. The efficient mediated microbial reduction of Cr(VI) is promising for rapid anaerobic removal of chromate.