Ceria-supported precious metals have great potential for use as water-gas-shift (WGS) catalysts in fuel processors for fuel-cell applications. In this paper, we review the mechanisms that have been proposed for these catalysts and discuss the deactivation that has been observed. Since a redox mechanism appears to explain the observations about the reaction best, we briefly review what is known about ceria reduction. We also discuss methods for enhancing catalytic activity through the use of additives. (c) 2005 Elsevier B.V. All rights reserved.