Cobalt supported on ceria and zirconia catalysts were prepared by the impregnation method. High cobalt dispersion was achieved by the introduction of citric acid. The properties of catalysts were studied in model reaction mixtures containing water vapour. It was observed that the presence of water decreased reducibility of the samples at elevated temperatures. This effect was strongly manifested in the ceria containing catalysts. Surface and bulk oxidation was observed when samples were heated up in the inert gas saturated with water vapour. The strongest surface oxidation effect was observed in the composite CeO2-ZrO2 oxide supported catalysts. (C) 2011 Elsevier B.V. All rights reserved.