Coke formation and metal dusting behaviors of electroplated Ni + nano-CeO2 particle coatings were studied in 24.4% CO-73.3% H-2-2.3% H2O at 650 C. The addition of CeO2 particles enhanced carbon deposition and pit formation on the Ni surface. The susceptibility of Ni + nano-CeO2 particle coatings to coke formation and metal dusting generally increased with the increase of CeO2 particle content in the coatings. Based on the analysis results of X-ray diffraction, X-ray photoelectron spectroscopy, and Auger electron spectroscopy, it seemed that the enhanced coke formation and metal dusting by CeO2 was related to the oxidation of Ni at the Ni/CeO2 interface due to the release of oxygen by CeO2 and the reaction of CeO2 with Ni during exposure. The subsequent reduction of resultant NiO to fine Ni particles accelerated carbon deposition and pitting attack. (c) 2007 The Electrochemical Society.