Raman spectroscopy was used to detect strained PdO in fully formulated Pd-based automotive exhaust-gas catalysts that had been subjected to high-temperature accelerated aging treatments. The presence of strained PdO provides evidence of Pd encapsulation by ceria-zirconia, as in a previous study of a model powder catalyst. The relationship between strained PdO and Pd encapsulation was further examined for other model catalysts, and major factors influencing the application of this detection method were identified. (C) 2003 Elsevier B.V. All rights reserved.