The BioGenerator is a unique microbial fuel cell for the conversion of hydrogen to electricity. It can be used in the hydrogen-based energy storage as a re-electrification device. This paper shows the results of the long-term stability testing of the BioGenerator. Using a bench scale bioreactor and electrochemical cell, it has been shown that the BioGenerator can achieve at least 3.8 years of continuous electricity generation without significant deterioration either in the biological or in the electrochemical components. The only part which was replaced twice a year was the anode in the electrochemical cell. The results of this work are a significant step towards the commercialization of the BioGenerator, especially in the energy storage sector. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.