The electromotive force (e.m.f) is calculated for solid oxide fuel cells (SOFCs) based on doped ceria electrolytes using biomass-produced gases (BPG, 14.7% CO, 14.2% CO₂, 15.3% H₂, 4.2% CH₄, and 51% N₂) as fuels and air as oxidant. It reveals that the BPG derived e.m.f. is very close to hydrogen when doped ceria is used as the electrolyte. A 35-m-thick samaria-doped ceria based single cell was tested between 450 and 650°C using BPG as fuel. Maximum power density of about 700 mW cm^–2 was achieved at 650 °C. The open-circuit voltage at 450 °C was 0.96 V, close to the calculated value. However, the cell power density using BPG as fuel was relatively lower than that using humidified hydrogen (3% H₂O), and close to that using humidified methane (3% H₂O). Impedance measurements indicate that the relatively lower power output may be attributed to the high anode--electrolyte interfacial polarization resistance when BPG is used as fuel.