The preparation of carburized CoMo with alumina, potassium or zirconium added and their activity for the water-gas shift reaction at 453 K were investigated on the basis of XRD, temperature-programmed desorption (TPD) after (H2O)-O-18 adsorption, transmission electron microscopy, and X-ray photoelectron spectroscopy. The carburized 5 wt%Al2O3/Co46.5Mo46.5K2Zr5 catalyst exhibited the highest CO conversion and TOF. The TPD experiment after (H2O)-O-18 adsorption showed that the Zr-containing catalysts produced Co6Mo6C1 from beta-Mo2C and Co metal, but the catalyst without zirconium produced MoO2 and Co3Mo. The presence of potassium significantly promotes water dissociation while zirconia prevented the oxidation of beta-Mo2C. The Al2O3 KZr-promoted CoMo catalyst exhibited a higher distribution of Co-0 and Co2+ than the catalysts containing either zirconium or potassium in the presence of the Co3+ ions. The Al2O3 KZr-promoted CoMo catalyst contained beta-Mo2C, small Co metal particles and Co6Mo6C1 along with zirconia, potassium and alumina. (C) 2010 Elsevier B.V. All rights reserved.