Microbial electrolysis cells (MECs) is an emerging technology for energy and resource recovery during waste treatment. MECs can theoretically convert any biodegradable waste into H-2, biofuels, and other value added products, but the system efficacy can vary significantly when using different substrates or are operated in different conditions. To understand the application niches of MECs in integrative waste biorefineries, this review provides a critical analysis of MEC system performance reported to date in terms of H-2 production rate, H-2 yield, and energy efficiency under a variety of substrates, applied voltages and other crucial factors. It further discusses the mutual benefits between MECs and dark fermentation and argues such integration can be a viable approach for efficient H-2 production from renewable biomass. Other marketable products and system integrations that can be applied to MECs are also summarized, and the challenges and prospects of the technology are highlighted. (C) 2016 Elsevier Ltd. All rights reserved.