Concerns over environmental protection have increased in recent years, leading to a search for new renewable energy sources for minimizing anthropological damage to both atmosphere and water bodies. Microbial Fuel Cells are inserted in such a context, since they can reduce the organic load of an effluent concomitantly with the production of bioelectricity. This study investigated three different sources of microorganisms, evaluating parameters such as carbon source concentration and temperature in energy efficiency. The electrical current generated by microbial activity in the oxidation of organic matter was monitored additionally with ionic conductivity and pH of the medium. Chemical Oxygen Demand was also determined towards an evaluation of the removal of organic matter. The Microbial Fuel Cell inoculated with Activated Sludge showed higher electrical current in comparison to other studies from the literature and a greater generation of electrical current and a high influence of conductivity on that efficiency was observed at 36 °C. As a conclusion, Microbial Fuel Cells can operate at both 4.0 gL-1 (COD mgO2 3,886.728) and 3.0 gL-1 (COD mgO2 3,124.573).