The aim of this study was to develop a microbial electrolysis cell (MEC) constructed with spiral wound electrode and to evaluate its effectiveness for wastewater treatment and methane (CH4) production. The spiral wound design can provide more than 60 m(2)/m(3) of specific surface area of the electrode and low internal resistance. With acetate as the substrate and increasing applied voltages from 0.7 to 1.3 V, the average current density and CH4 production rate increased from 46 to 132 A/m(3) and from 0.08 to 0.17 m(3)/m(3) d, respectively. With the increasing applied voltages, the energy efficiencies decreased from 157% to 69%, while the COD removal rates increased from 0.31 to 0.69 kg COD/m(3)d. The optimal applied voltage of the spiral-wound-electrode MEC was about 0.95V. Fed with dairy wastewater, the MEC also showed good performance with the average current density of 24 A/m(3), CH4 production rate of 0.03 m(3)/m(3) d, energy efficiency of 66%, and COD removal rate of 0.20 kg COD/m(3) d. (C) 2015 Elsevier Ltd. All rights reserved.