BACKGROUND: Hydrogen peroxide (H₂O₂) is an important chemical product, and this study investigated its synthesis at the cathode of a microbial fuel cell (MFC) system using spectrographically pure graphite (SPG) rods as cathode electrode.

RESULTS: Electrochemical methods showed that oxygen reduction reaction (ORR) on SPG mainly followed the two‐electron pathway yielding H₂O₂, while, the optimal condition for H₂O₂ production was in 0.1 mol L⁻¹ Na₂SO₄ electrolyte. When SPG was used as the cathodic electrode in the MFC system, H₂O₂ concentration reached 78.85 mg L⁻¹ after 12 h operation with an external resistance of 20 Ω (H₂O₂ production rate was 6.57 mg L⁻¹ h⁻¹). Coulombic efficiency, current efficiency and COD conversion efficiency were 12.26%, 69.47% and 8.51%, respectively. Repeated experiments proved this system had a stable operating performance.

CONCLUSIONS: H₂O₂ was synthesized at the cathode of an MFC, and this study provides a proof‐of‐concept demonstration to realize the process of synthesizing H₂O₂ with wastewater. Copyright � 2010 Society of Chemical Industry