In this paper the adsorption and oxidation of CO on nanocrystalline Au/gamma-Fe2O3, Au/alpha Fe2O3, gamma-Fe2O3 and a series of mixed ferrite with MnxZn1-xFe2O4 composition are investigated. The catalysts were prepared by co-precipitation method and characterized using X-ray diffraction (XRPD), specific surface (BET), transition electron spectroscopy (TEM) and magnetization measurements. A temperature programmed desorption (TPD) study of the water and CO interaction with nanocrystalline adsorbents is presented. The catalytic activities towards CO oxidation increased in the following order: gamma-Fe2O3 < MnxZn1-xFe2O4 < Au/gamma-Fe2O3.