The effects of PbCl2 on the selective catalytic reduction of NO with NH3 over vanadia-based catalysts were studied with BET, XRD, SEM, XPS, NH3-TPD, NH3 chemisorption, FT-IR and catalytic activity measurements. The results showed that PbCl2 deactivated the catalysts to a very high extent. The doping of PbCl2 could decrease the surface acidity, especially that of Bronsted acid sites. XPS characterization reveals that the presence of PbCl2 resulted in the transformation of V5+ into V4+, which decreased the reducibility of vanadia species. Based on the analysis of physical and chemical properties of the catalysts, the PbCl2-poisoning mechanism model of the vanadia-based SCR catalysts was proposed. (C) 2014 Elsevier B.V. All rights reserved.