The aim of this study is to investigate the effect of the number of sediment microbial fuel cells (SMFCs) with different configurations on the electricity generation in open channels. For this purpose, two open channels, one with three and another with four SMFCs, were operated over a long period of time and their performances were analyzed. Individual SMFCs followed an almost similar trend for electricity generation during the operation time. In addition, it was found that three-SMFC stacking in series mode produced a relatively higher maximum power density (18 mW m(-2)) than four-SMFC stacking (16 mW m(-2)). However, in parallel mode, four-SMFC stacking had a higher maximum power density of 90 mW m(-2) compared to three-SMFC stacking with maximum power density of 78 mW m(-2). These findings indicate that different numbers of cells significantly affect electricity generation depending on the type of SMFC configuration in the channel. The results would be helpful for application of SMFCs in large-scale. (C) 2016 Elsevier B.V. All rights reserved.