The anode microstructural evolution is correlated to its electrochemical characteristics during a long time discharge for conventional nickel-yttria-stabilized zirconia composite anode. Self made anode performance degraded with operation time in humidified hydrogen, with the increases of both ohmic and polarization losses. The anode samples after different discharging times were analysized by 3-dimensional microstructure reconstruction based on focused ion beam-scanning electron microscopy technique. Nickel connectivity, nickel-yttria-stabilized zirconia interface area and the active three-phases-boundary length were correlated to the anode degradation. The influences of bulk gas humidity and current density were also investigated to reveal their contributions to the anode degradation. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.045203jes] All rights reserved.