Traditional Ni/YSZ anode SOFCs were modified by Sn, Cu and Ag by an infiltration method to obtain Sn-Ni, Cu-Ni and Ag-Ni alloy anode catalysts on the anode. The obtained maximum power density of Ni/YSZ, Sn-doped Ni/YSZ, Cu-doped Ni/YSZ, and Ag-Ni/YSZ cells fuelled by simulated biogas (14 mL min(-1) CH4, 7mL min(-1) CO2 and 7mL min(-1) N-2) at 750 degrees C were 0.101, 0.272, 0.085 and 0.102 W cm(-2) respectively. Stability tests of SOFCs in biogas revealed that the stability of Sn-Ni/YSZ and Ag-Ni/YSZ cells in operation was greatly improved compared to the undoped Ni/YSZ cell. Both Sn-Ni/YSZ and Ag-Ni/YSZ cells stably operated for 48 h, but Ni/YSZ cell ceased operation after 19 h due to carbon deposition. The addition of small amount of Cu did not enhance the anti-coking ability. Other than with the severe carbon deposition on the Ni/YSZ anode surface, no observable fibrous carbon could be identified on the Sn-Ni/YSZ and Ag-Ni/YSZ anode surfaces. (C) 2019 The Electrochemical Society.