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[Display omitted] • The methanogenic performance was better when the applied voltage was 0.8 V. • Clostrodium and Methanosaeta were the most dominant microbial populations. • MES-Cathode was more tolerant to the effects of higher NH 4 +-N concentration. • CH 4 was produced mainly via hydrogenotrophic methanogenic pathway in MES-Cathode. • MES produced CH 4 via SOAB, hydrogenotrophic archaea if acetoclastic pathway curbed. Microbial electrosynthesis (MES) has great potential for energy and resource recovery in wastewater treatment and has therefore gradually become a popular research topic. In this study, MES with an applied voltage (0.6 V, 0.8 V and 1.0 V) significantly improved biogas production (36.0 %, 52.3 %, and 59.1 %, respectively) compared with the control (without electrodes). Analysis of microbial community structure revealed that Clostridium and Methanosaeta had the highest relative abundance in all reactors. The abundances of Acetivibrio and Geobacter dominated the bioanode, and methane production was mainly mediated by the acetoclastic methanogenic pathway. On the biocathode, the abundances of Methanolinea and Methanothermobacter were higher than those of other microbes, and methane was produced primarily through the hydrogenotrophic methanogenic pathway. When the acetoclastic methanogenic pathway in the biocathode was inhibited, MES could efficiently produce methane through other pathways. In addition, MES was more tolerant to the effects of high NH 4 +-N concentrations than anaerobic digestion (AD). These results suggest that applying voltage to the bioanode and biocathode could better improve the efficiency of methane production. [ABSTRACT FROM AUTHOR]