Real-time measurement of volatile fatty acids (VFA) in anaerobic digestion (AD) is crucial for process monitoring and management. It is essential for establishing demand-driven biogas production, however, to date it is not commercially available. A novel microbial electrochemical sensor for inline measurement of acetate and other VFA in AD is proposed. The measurement range as well as the measurement resolution and dynamic behavior of the biosensor were investigated under flow conditions. For application in AD the achieved measurement range is still too low, therefore, measures to improve it as well as further application properties of the sensor are discussed.