Quantitative assessment of anode contribution to cell performance has been investigated under various polarization in three stack repeating units made of 10 cm x 10 cm planar anode-supported solid oxide fuel cells. The measurement is performed in-situ by inserting an ultra-thin Pt probe at the anode/electrolyte interface. The results reveal that the polarization resistance accounts for more than 90% of the total cell resistance when the cell is operated under the activation and concentration polarizations, respectively. The anode almost has no effect on cell degradation when the cell is operated under activation polarization. However, the anode has an obvious contribution to the cell degradation when the cell is operated under ohmic and concentration polarization, where the anode voltage increases by 23.36%/100 h and 512.28%/100 h, respectively. The anode operated under concentration polarization has twenty times of contribution to cell degradation than that of the ohmic polarization. However, when the cell is operated under the ohmic polarization, the main degradation comes from the ohmic resistance caused by the anode. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.