The aim of this work was to study the effect of pH on electricity production and contaminant dynamics using microbial fuel cells (MFCs). To investigate these effects, an air-cathode MFC was used to treat urban wastewater by adjusting the pH between 6 and 10. The short-term tests showed that the highest power production (0.66 W.m(-3)) was at pH 9.5. The MFC operation in continuous control mode for 30 days and at the optimal pH improved the performance of the cell relative to power generation to 1.8 W.m(-3). Organic matter removal (77% of influent COD) and physical ammonium loss were directly influenced by pH and followed the same behavior as the power generation. At a pH higher than the optimal one, anodic bacteria were affected, and power generation ceased. However, biological nitrogen processes and phosphorus dynamics were independent of the exoelectrogenic bacteria. (C) 2010 Elsevier Ltd. All rights reserved.