The concept of the microbial fuel cell (MFC) has existed for over 100 years, but only since the last decade its practical implementation in waste water treatment has been realized in scales up to 1000L. This review article shows available strategies to increase the limiting extracellular electron transfer (EET) for anode space of MFCs. Therefore, organism-based improvements as well as the effect of (bio)polymers and redox mediators on ETT will be demonstrated.