The photoluminescence (PL) and PL excitation spectra of pure and Pt-loaded CeO2 powders were measured, and the PL peaks from the Sm3+ impurity were observed. We found that, as the Pt concentration increases, the peak intensity decreases and the PL excitation band blueshifts. These relationships can be explained by considering electron transfer and difference in work function between CeO2 and Pt. Moreover, we found a quantitative relationship between the blueshift and the difference in work function. These results suggest that the degree of contact and extent of electron transfer between CeO2 and Pt can be estimated from PL spectroscopy. (c) 2005 Elsevier B.V. All rights reserved.