The selective CO oxidation in H-2-rich gas over K2CO3-promoted Rh/SiO2 (K2CO3-Rh/SiO2) catalysts was investigated, and the results were compared with those of Rh/SiO2 catalysts. K2CO3-Rh/SiO2 catalysts were able to realize almost complete removal of CO. The additive effect of K2CO3 was dependent on the preparation method and on the K2CO3 amounts. K2CO3-Rh/SiO2 catalyst prepared by the sequential impregnation method with molar ratio K/Rh = 3 exhibited high performance. According to the characterization results, the catalyst had highly dispersed Rh metal particles partially covered with K2CO3. (C) 2004 Elsevier B.V. All rights reserved.