The aims of this research were: (i) to develop and test a new, low cost, organic membrane (LCM) in an air-cathode, single chamber microbial fuel cell (MFC), and (ii) to compare its characteristics with those of an MFC equipped with a Nafion® 117 membrane (NF). The internal resistances (Rint) were 112 and 110 Ω using LCM and NF, respectively, whereas the maximum volumetric powers (PV,max) were 2146 and 14,246 mW/m3 for LCM and NF, respectively. The relatively low value of Rint of the MFC equipped with LCM was encouraging. Furthermore, the Rint of the NF-equipped MFC was of the same order.PV,max delivered with LCM was 15% of that with NF. However, the cost ratio LCM/NF was very low, ($14/m2)/($1733/m2) ∼ 0.8%. These results point out to a trade-off between sacrificing some power output of the cell (85%) but achieving outstanding savings on membrane costs (99.2%).