The presence of Ce was found to be potentially beneficial for the iso-butane oxidation activity of 0.5 wt% Pt/Al2O3 catalysts after reduction treatments. Temperature-programmed reduction (TPR) experiments showed that the addition of Ce to Pt/Al2O3 resulted in a bimetallic surface interaction which affected surface reducibility. X-ray photoelectron spectroscopy (XPS) indicated that the nature of Pt-Ce interaction varied depending on the loading of Ce. After impregnation and calcination in air, the presence of Ce, at Ce:Pt greater than or equal to 8:1 atomic ratio, generally resulted in poorer oxidation activity relative to Pt/Al2O3 with higher temperatures required to achieve the same level of i-C4H10 conversion. At a lower Ce loading (Ce:Pt=0.5:1 atomic ratio), oxidation activity was not so adversely affected. In general, the activity of the Pt catalysts increased after initial testing in the reactant mixture. Reduction of a 0.5 wt% Pt/Al2O3 catalyst resulted in considerable loss of activity. The addition of Ce appeared to help prevent this deactivation. TPR profiles indicated that the existence of an interaction between Pt and Ce in PtCe/Al2O3 samples was associated with improved activity following reduction. (C) 1998 Elsevier Science B.V. All rights reserved.