(T)he interaction of deuterium with Ce0.6Zr0.40, synthesised by a co-precipitation technique, is discussed on the basis of the sample's bulk and surface composition and the presence of trace amounts of silicon. Redox cycling resulted in surface cerium enrichment, which, however, only moderately affected the interaction of the material with D,. Addition of a trace amount of chloride ion to the oxide surface promoted both HID scrambling and vacancy creation. Chloride ion was also found to prevent the surface cerium enrichment induced by redox cycling, (c) 2005 Elsevier B.V. All rights reserved.