A sulfur-tolerant Pt catalyst has been developed for fuel processors being developed for use with fuel cells, using a fluorite-type Ce0.8Gd0.2O1.9 support. The catalyst calcination temperature is Crucial to ensure the maintenance of sulfur tolerance. The catalyst calcined at 800 degrees C retained its activity and selectivity for entire 100-h test period in the steam reforming of iso-octane with >= 300 mu g/g of sulfur, whereas the catalyst calcined at 600 degrees C obviously lost activity in this course. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) for CO and CO/H2S adsorption was performed to characterize the nature of the Pt sites and to evaluate their ability to tolerate sulfur. Strongly electron-deficient Pt sites, evidenced by a CO adsorption band at V-max 2104-2108 cm(-1), were immune to sulfur poisoning and were uniformly formed with the calcination at 800 degrees C. In addition, thiophene sulfur was completely converted into H2S and likely complied with a redox mechanism. (c) 2007 Elsevier Inc. All rights reserved.