Chromium deposition and poisoning at double-perovskite type SmBaCo2O5.8 (SBCO) cathodes of solid oxide fuel cells (SOFCs) are studied. The electrochemical activity of SBCO cathodes for the O-2 reduction reaction degrades quickly in the presence of a chromia-forming metallic interconnect, indicating that SBCO is not a Cr-tolerant and resistance cathode. The results indicate that the deposition of Cr species is essentially induced by the segregated BaO on the SBCO surface, leading to the formation of BaCrO4. The deposition and formation of BaCrO4 phase accelerates the abstraction of Ba from the SBCO, resulting to the decomposition of SBCO double perovskite structure and the loss of electrochemical activity for the O-2 reduction reaction. (C) 2015 Elsevier Ltd. All rights reserved.