The most frequent by-product of the majority of industries is wastewater. Wastewater treatment alone consumes a significant amount of energy until being disposed of. Microbial electrolysis cells (MECs) are the biohydrogen production technology that arrived from a combination of electrolysis and microbial fuel cell technologies. Using electrochemically active microorganisms, MECs may transform organic material into hydrogen or several side products without harming the environment. MECs typically combine the catalytic conversion of organic substances on the anode side with the chemical reaction of hydrogen on the cathode side. So as a result, the quantity of hydrogen gas is produced under anaerobic conditions. In this book chapter, along with present difficulties and unrealized potential of MECs, the system architecture, operational parameters, integration of MECs with different processes like thermoelectric microconverter, anaerobic digestion-coupled system, current application, and future aspects of MECs is explored.