We study the methanation of CO2 catalyzed by ceria doped with Ni, Co, Pd, or Ru. Ce0.96Ru0.04O2 and Ce0.95Ru0.05O2 perform best, converting 55% of CO2 with a 99% selectivity for methane, at a temperature of 450 C. This is comparable to the best catalysts found previously for this reaction. Ce0.95Ru0.05O2 was characterized by XRD, electron microscopy, BET, XPS, IR spectroscopy, and temperature-programmed reaction with Ar, H-2, CO, and CO2 + H-2. Steady-state methanation was studied at several temperatures between 100 and 500 degrees C. We find that the methanation reaction takes place on the reduced Ce0.95Ru0.05O2, and the role of the dopant is to make the reduction possible at lower temperature than on pure ceria. We discuss the potential for local and global effects of the dopant on catalytic chemistry. (C) 2010 Elsevier Inc. All rights reserved.