The relationship between the Chromium (Cr) concentration in the porous (La,Sr) MnO3 (LSM) cathode and the polarization resistance was examined at accelerated Cr poisoning conditions. By supplying Cr vapor (p(Cr) similar to 10(-8) atm) to the porous LSM cathode the polarization resistances were increased significantly. Secondary ion mass spectrometry (SIMS) analysis of the LSM cathode suggested that an increase of Cr concentration levels both at the surface and at the triple phase boundary (TPBs) under polarization. The precise Cr concentration in the porous LSM cathode was successfully determined by SIMS to be in the orders of 0.0001-1 wt.% levels. The deposited Cr at the TPB effectively reduced the cathode performance under polarization; and the deposited Cr concentration at the TPB was above 1 wt.% in the Cr-poisoned cells. The polarization resistance increased with the Cr-concentration at the TPBs as well as at the cathode surface areas. (c) 2012 Elsevier B.V. All rights reserved.