A new approach that improved the dechlorination and mineralization of 4-chlorophenol (4-CP) was demonstrated in a sequential biocathode-bioanode bioelectrochemical system (BES) with mixed photosynthetic bacteria (PSB). The biocathode with additional PSB inoculation showed higher 4-CP dechlorination efficiency (DE) and maximum current (81.8 +/- 2.9%, 0.021 +/- 0.002 A) than that at abiotic cathode (45.3 +/- 3.7%, 0.011 +/- 0.002 A) (P < 0.005). Light response in biocathode BES with or without PSB ascertained the important role of PSB played in the dechlorination and current generation. Dechlorination and mineralization of 4-CP was achieved in the sequential biocathode-bioanode BES, which could be further enhanced with PSB inoculation in both cathode chamber and anode chamber. 4-CP DE in the cathode chamber was improved from 55.0 +/- 2.0% to 78.8 +/- 4.9%, and the phenol degradation in the anode chamber was improved from 65.3 +/- 2.1% to 71.3 +/- 1.4%. This study directed a new way for improving dechlorination at biocathode and product degradation at bioanode with PSB inoculation in BES. (C) 2014 Elsevier Ltd. All rights reserved.