This paper examines the effect of sulfation of vanadia-titania binary solid prepared by sol-gel process on its activity for the selective catalytic reduction (SCR) of NO with NH3. Sulfated and unsulfated vanadia titania have been characterized by means of N-2 adsorption-desorption at 77 K, XRD, TGA, propan-2-ol conversion as acid test, H-2-TPR measurements, EPR, XPS and Raman spectroscopies. The main results of this study highlight the interaction of sulfate ions with vanadia species. The ternary catalyst VTiS exhibits a high activity compared to binary TiS or VTi samples. It is concluded that sulfate species improve the superficial acidity of solid and interact with vanadia leading to a better reducibility of VTiS oxide. (c) 2006 Elsevier B.V. All rights reserved.