A catalyst composition comprising a vanadate represented by the formula XVO4/S, wherein XVO4 stands for a Bi-, Sb-, Ga- and/or Al-vanadate optionally in mixture with one or more rare earth metal-vanadates, or in mixture with one or more transition metal-vanadates, or in mixture with one or more transition metal-vanadates and one or more rare earth metal-vanadates, and S is a support comprising TiO2, optionally in combination with a dopant and a process for the preparation of such catalyst compositions.