This special issue of ChemSusChem is dedicated to the field of microbial electrochemistry, with a special emphasis on microbial fuel cells. The issue contains invited papers from leading groups in a wide range of aspects ranging from fundamental biological and electrochemical understanding, material research, and system engineering to questions referring to potential applications and economic feasibility. This broad range of contributions is exemplified on the cover picture, which contains graphs, for example, from contributions by Zhao et al., Hu et al., Torres et al., and Bond et al. For a more complete list and description of contributions, please see the editorial on page 959 ff. This selection can be only a fragmentary view of the rapidly growing research field, and many excellent groups could not be considered due to the limited space of such an issue.