Pt-supported on mesoporous SBA-15 catalysts (Pt/SBA-15) have been investigated for selective catalytic reduction of NO by propene in excess oxygen. Catalytic activity of Pt/SBA-15 can be improved by the post-synthesis modification of Al into SBA-15. The resulting material (AlSBA-15) retains a hexagonal order and physical properties of the parent SBA-15 and shows new acid sites. Increased acid sites are confirmed by NH3-TPD. Medium acid site appeared at 200 degrees C and broad strong acid site appeared above 250 degrees C. A certain degree of support acidity of Pt/AlSBA-15 increased the NO conversion, but when there are too many acid sites, carbon deposition becomes extensive and lead to decrease the NO conversion. The influence of different Pt loadings on the catalytic properties was also investigated.