H-2-CO mixtures were fed to anode-supported solid oxide fuel cell (SOFC) Ni-YSZ/YSZ/GDC/BSCF to investigate the cell electrochemical performance and carbon deposition on the anode. Reasonable power density (similar to 0.8 W cm(-2)) was achieved with different H-2-CO ratios as fuels. By analyzing the electrochemical impedance spectroscopy (EIS) data, it was found that the medium frequency resistance increased with the increasing CO content, which indicated it was most likely associated with the anode charge transfer process. When ratio of H-2:CO was around 2, CO mainly participates in the water gas shift reaction; and with the increasing CO content in the mixtures, CO also partly was involved in electrochemical oxidation. The cells could operate stably for all H-2-CO mixtures about 10 h without failure at a constant current of 50 mA cm(-2). After the cells were tested, no carbon deposition was observed for the pure CO case, but with the presence of H-2, carbon was observed. This phenomenon proves that the presence of H-2 in H-2-CO mixtures promotes carbon deposition of CO. We firstly explored the carbon deposition area and found that carbon formation occurred only on the anode surface, which might be mainly caused by CO reduction reaction due to shifting the reaction equilibrium towards reverse syngas formation. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.