Microbial Fuel Cell (MFC) is a new device for simultaneous electricity production and wastewater treatment. The major concern of this technique is the high operational cost that is caused by Nafion 117 used as a Proton Exchange Membrane (PEM) and Pt as a cathode catalyst for oxygen reduction. Sulfonated poly ether ether ketone (SPEEK) was used as a PEM in MFC for this study. The results indicate that even though the power production of MFC with SPEEK (773 mW.m(-2)) was lower than Nafion 117 (106.7 mW.m(-2)), it is more cost effective, due to its lower price. Our cost evaluation suggests that the use of SPEEK in power production is about two times more cost effective than that of Nafion 117. Furthermore, its chemical oxygen demand (COD) removal (88%) is higher than Nafion 117 (76%); and thus, SPEEK, given substantial increases in power density may be a promising PEM in MFCs at an industrial scale. (C) 2013 Elsevier B.V. All rights reserved.