This study reports the activity of ionic substituted bimetallic Cu-Ni-modified ceria and Cu-Fe-modified ceria catalysts for low-temperature water gas shift (WGS) reaction. The catalysts were synthesized in nano-crystalline size by a sonochemical method and characterized by XRD, TEM, XPS, TPR and BET surface analyzer techniques. Due to the ionic substitution of these aliovalent base metals, lattice oxygen in CeO 2 is activated and these catalysts show high activity for WGS at low temperature. An increase in the reducibility and oxygen storage capacity of bimetallic substituted CeO 2, as evidenced by H 2-TPR experiments, is the primary reason for the higher activity towards WGS reaction. In the absence of feed CO 2 and H 2, 100% conversion of CO with 100% H 2 selectivity was observed at 320°C and 380°C, for Cu-Ni-modified ceria and Cu-Fe-modified ceria catalysts. Notably, in the presence of feed H 2O, a reverse WGS reaction does not occur over these ceria modified catalysts. A redox reaction mechanism, involving oxidation of CO adsorbed on the metal was developed to correlate the experimental data and determine kinetic parameters. © 2012 Elsevier B.V.