Hydrogen is gaining international attention as a sustainable energy carrier with the potential to replace fossil fuels. A cutting edge technology called a microbial electrolysis cell (MEC) can achieve sustainable and clean hydrogen production from a wide range of renewable biomass. A large number of substrates have been used as fuel sources. The major substrates that have been tested include wastewaters, fermentable and non-fermentable organic materials. This article mainly reviews the various substrates that have been used in MECs so far, also their resulting performance, as well as future potential substrates discussed. Besides, in this paper, a short review of recent advances in electrode material and a configuration of both the anode and cathode in MECs are provided. (C) 2014 Elsevier Ltd. All rights reserved.