Laboratory-scale microbial fuel cells are often operated with a constant electrical load. Meanwhile, variations in influent strength and quality, as well as the processes of biofilm growth and decay lead to significant changes of the MFC internal resistance over time. This inevitably results in a mismatch between the internal and the external resistances therefore decreasing MFC power output. This study presents the concept of MFC operation with intermittent connection of the electrical load (external resistance). The efficiency of the proposed method is demonstrated by MFC operation with external resistances significantly below the MFC internal resistance and comparing power outputs obtained using either constant or intermittently connected resistances. Crown Copyright (C) 2012 Published by Elsevier B.V. All rights reserved.