The influence of chromium poisoning on the long-term stability of the oxygen exchange kinetics of the promising IT-SOFC cathode materials La0.6Sr0.4CoO3-delta (LSC) and Nd2NiO4+delta (NDN) is investigated in-situ by dc-conductivity relaxation experiments. The as-prepared LSC and NDN samples show high chemical oxygen surface exchange coefficients k(chem). After the deposition of a 10 nm thick Cr-layer onto the surface, k(chem) of LSC decreases to 50% of the initial value. Additional chromium deposition of 20 nm on LSC leads to a further decrease of k(chem) to 27% of the initial value. In contrast, the effect of a 10 nm thick Cr-layer on k(chem) of NDN is negligible. Even with additional 20 nm of chromium and a total testing time of 1750 h, the nickelate retains a k(chem) of 60% of the initial value. X-ray photoelectron spectroscopy (XPS) of the degraded. LSC shows a significantly altered surface cation composition with Sr-enrichment down to 30 nm depth while XPS analysis of the degraded NDN reveals a thin surface zone of approximately 30 nm containing nickel and chromium. In contrast to LSC, the changes in the surface composition of NDN due to Cr-poisoning ultimately had only a minor influence on the surface exchange properties. (C) 2010 Elsevier B.V. All rights reserved.