In solid oxide fuel cell operation, electrical current plays an important role in the air electrode interaction with electrolyte and interconnect and long-term cell performance. In this study. (La0.8Sr0.2)(x)MnO3 (LSM) air electrodes with different stoichiometries (x = 0.95, 1, and 1.05) are fabricated on the surface of yttria stabilized zirconia (YSZ) and then sandwiched with AISI 441 stainless steel interconnect. The simulated half cells are thermally treated at 800 degrees C for 500 h under a 200 mA cm(-2) current density in dry air. YSZ/LSM interfacial interaction and the reaction of volatile chromium species on the LSM surface are characterized. Different LSM stoichiometry leads to different interfacial reactions and Cr deposition amounts. Mn is a critical species for the Cr deposition under polarization. Excessive Mn in LSM lessens the formation of La-containing phase at the YSZ/LSM interface and accelerates Cr deposition. Deficient Mn in LSM leads to extensive interfacial reaction with YSZ, forming more La-containing phase and inhibiting Cr deposition. (C) 2011 Elsevier B.V All rights reserved.