The synthesis of value-added compounds other than acetate at high rates while utilizing cheap electrode materials is one of the current difficulties faced in microbial electrosynthesis. The present study investigated the production of higher chain volatile fatty acids from the reduction of ethanol and CO2 using unmodified carbon felt at different negative cathode potentials viz. −0.8, −1.0 and −1.2 V vs Ag/AgCl. Propionic acid was produced as secondary main product after acetic acid. The applied voltage of −1.2 V reported the highest amount of acetic acid with production rates of 949 mg L−1 d−1 (15.81 mM d−1). The increased cathode potential from −0.8 to − 1.2 V enhanced the maximum acetic acid production. The maximum acetic acid production achieved at a voltage of −1.2 V was 1.72 and 1.17 folds higher than MES operation at −0.8 and −1.0 V, respectively. Highest amount of propionic acid with the production rates of 322 mg L−1 d−1 (4.34 mM d−1) was obtained at −1.0 V, which was 1.20 and 2.12 times higher than the MES operation at −0.8 and −1.2 V, respectively. Scanning electron microscopy revealed dense biofilm and strong attachment of diverse microorganisms on the biocathode. © 2023 Elsevier B.V.