The nickel/yttrium-stabilized zirconia (Ni/YSZ) anode-supported solid oxide fuel cells (SOFCs) have been operated under various simulated syngases at different temperatures to investigate the degradation behavior of the cells caused by carbon deposition. The results show that the carbon morphology and the cell performance degradation are influenced significantly by the operation temperature. The stability of the cell fueled with syngas can be improved by applying a constant current, but the cell degraded quickly after carbon deposition. The microstructure damage is close to the anode surface and leads to a conductivity decrease, which is an important reason for the cell degradation and failure at 750 degrees C. Conversely, the degradation behavior at 650 degrees C is mainly due to solid carbon deposits inside of the anode that impede fuel diffusion and electrochemical reactions on the anodic side. The effect of carbon deposition on the microstructure degradation is also investigated using transmission electron microscope. (C) 2010 Elsevier B.V. All rights reserved.