Bioelectrochemical systems can be used to energy-efficiently produce hydrogen peroxide (H2O2) from wastewater. Organic compounds in the wastewater are oxidized by microorganisms using the anode as electron acceptor. H2O2 is produced by reduction of oxygen on the cathode. In this study, we demonstrate for the first time production of high concentrations of H2O2 production from real municipal wastewater. A concentration of 2.26 g/L H2O2 was produced in 9 h at 8.3 kWh/kgH2O2. This concentration could potentially be useful for membrane cleaning at membrane bioreactor wastewater treatment plants. With an acetate-containing nutrient medium as anode feed, a H2O2 concentration of 9.67 g/L was produced in 21 h at an energy cost of 3.0 kWh/kgH2O2. The bioelectrochemical reactor used in this study suffered from a high internal resistance, most likely caused by calcium carbonate deposits on the cathode-facing side of the cation exchange membrane separating the anode and cathode compartments.