A model vanadia/silica interface has been prepared by vapour deposition of vanadium-oxy-triisopropoxide onto the native oxide layer of a silicon wafer. The VO(x)/SiO2/Si model system has been used to investigate the morphological and chemical changes occurring with vanadia/silica catalysts when they are exposed to different gas atmospheres. Atomic force microscopy and X-ray photoelectron spectroscopy have been used to follow these changes. The studies show that exposure of the vanadia/silica interface to conditions prevailing during the selective reduction of NO by NH3 results in temperature dependent morphological changes, while the oxidation states of the vanadia species reflected by the ratio V(III)/V(V) change only little during the surface reconstruction.