Mesoporous SO2 oxidation catalysts were prepared by impregnation of a sol-gel prepared vanadia-silica support with various amounts of cesium sulfate or mixtures of alkaline sulfate species (Na or K). The resulting catalysts were characterized by adsorption-desorption isotherms of nitrogen at 77 K, in situ evolution of crystallinity by X-ray diffraction, NH3-DRIFT, XPS, transmission electron microscopy, dispersive X-ray analysis, and X-ray fluorescence spectrometry. Catalytic tests in oxidation Of SO2 in diluted gases (1 vol.%) showed that these systems were very active. A dependence on the alkaline metal loading was also evidenced. (C) 2004 Published by Elsevier B.V.