In the present work, a theoretical investigation of water interaction with cluster models for fragments of V-W-O catalysts surface was performed to study the strength of Lewis and Bronsted sites. The clusters representing two adjacent metal sites in pentacoordinated oxygen environment were chosen as working models to mimic the crystalline vanadia-like species exposing (0 0 1) V2O5 face. Geometry, OH stretching frequencies and water binding energy were chosen as three computed parameters to characterise the Lewis acid and basic sites and Bronsted acid sites situated in varying environment. It was shown that for Bronsted sites these parameters for both the site itself and its adduct with water molecule varied coherently and correlated well with the site acidity. For Lewis sites the problem was more complex and only water binding energy combined with characteristic adsorption geometry was a good index for the strength of both types of sites: basic and acid ones. (C) 2004 Elsevier B.V. All rights reserved.