A series of Sn-modified Co3O4 catalysts with different Co/Sn molar ratios were prepared via coprecipitation method and characterized by N-2-BET, XRD, H-2-TPR, XPS and FTIR techniques. The addition of a small amount of Sn into Co3O4 has a mild influence on its CO oxidation activity, but promotes its water resistance evidently. The major reason is attributed to the effective suppressing of water adsorption on the catalyst surface by Sn addition, as testified by FTIR results. Co0.90Sn0.10, a catalyst with a Co/Sn molar ratio of 0.90/0.10, shows the potential to be used in some real emission control processes for CO oxidation due to its reasonable activity and evidently improved reaction stability in the presence of water vapour. (C) 2015 Elsevier B.V. All rights reserved.