Hydrogen production by microbial electrolysis cells (MECs) provides a completely new avenue for the production of hydrogen from biomass. The key competitive advantage of this technology compared with previous techniques for biohydrogen generation is that the biomass can be utilized fully for H2 conversion. This review provides a brief overview of recent advances in research on electrochemically active bacteria, electrode materials, MEC design and performance and fuel sources of MECs. Enhancing the hydrogen-production rate and lowering the energy input are the main challenges of MEC technology. The review concludes that breakthroughs in the development of efficient cathode material, scalable MEC design and cost-efficient pretreatment processes are needed for future studies.