Chromium poisoning of the air electrode of solid oxide fuel/electrolyzer cells is a critical issue when stainless steel with high Cr content is used as an interconnect material. The mechanism of the diffusion and deposition of the Cr species is not totally clear yet. In this work, an yttria-stabilized zirconia electrolyte (YSZ)/strontium-doped lanthanum manganite electrode (LSM)/AISI 441 alloy interconnect tri-layer structure has been fabricated by screen printing in order to simulate the working environment of a real cell. The samples are thermally treated in moist air atmosphere at 800 degrees C for up to 500 h. The porous LSM layer thickness has been controlled to investigate the Cr distribution in the porous layer and the diffusion behavior of the Cr species. The microstructure and elemental analysis show that Cr species diffuses into the porous LSM layer and deposits on the LSM surface. The deposition occurs simultaneously with the LSM grain growth. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.