Indonesia is one country with high electricity consumption. Electrical energy demand in Indonesia is creasing in past few years. However, the use of crude oil as the source of energy is still dominating, while the reserve of crude oil in Indonesia is depleted. Therefore it has sparked a growing range of research done in the direction of innovative technologies that are more effective, efficient, and environmentally friendly to produce of sustainable electrical energy, such as Microbial Fuel Cell (MFC). In principle MFC technology will degrade the substrate through the activity of microorganisms to produced electrical energy. The current study focused on the utilization of tahu industry wastewater as a substrate on dual chamber MFC system equipped with a salt bridge as proton exchange. Variation circuits in the MFC system was conducted by installing the system in series, parallel and combination also was conducted variation of incubation time on the substrate for one day, one week, and one month. The optimal results of both variations will be applied to the use of tahu industry wastewater as a substrate. From this study, the highest electrical energy generated in term of power density 260, 27 mW/m2. This value obtained in MFC reactor parallel with one week of incubation time.