Carbon mesh (CM) materials are modified by nitric acid or hydrazine hydrate to test whether the performance of MFCs could be improved. The power densities of MFCs using nitric acid-treated anode (CM-NA) and hydrazine hydrate-treated anode (CM-HA) are improved by 24% (811 +/- 24 mW m(-2)) and 19% (777 +/- 35 mW m(-2)) as compared to the unmodified control (655 +/- 7 mW m(-2)). All MFCs using modified cathodes (CM-NC/Pt, CM-HC/Pt) also show higher performance in electrochemical response and power generation. The maximum power densities of reactors using CM-NC and CM-HC are respectively 811 +/- 29 mW m(-2) and 792 +/- 16 mW m(-2), which is 24% and 21% higher than the control. XPS and SEM results show that the performance improvement is related to the changes of surface functional groups and surface area. Further, the power densities with both anode and cathode modified by nitric acid (NN) and hydrazine hydrate (HH) are found to be increased by 38% (905 +/- 15 mW m(-2)) and 31% (860 +/- 30 mW m(-2)), respectively. CV measurements indicate that the electricigens have much higher activity. These results demonstrate that the power output of MFCs can be further increased through coupling of anodic and cathodic modification. (C) 2012 Elsevier B.V. All rights reserved.