Reduction of nitrogen oxides (NO,) in a lean exhaust gases has become one of the most important environmental concerns. This study compared the performances of DeNO(x) and the properties of silver/mesoporous aluminosilica synthesized by different methods. Silver nanoparticles were obtained after calcination of the materials prepared by incipient wetness or by the excess solvent impregnation of Al-SBA-15 support by silver nitrate. On the other hand, the silver nitrate was introduced on the synthesis gel of SBA-15. The solid product was used as support to deposit aluminium. The effect of synthesis method on silver incorporation and the porous structure of the resulting solids has been examined. Some techniques had been applied, such as: elemental analysis, X-ray diffraction (XRD), N-2 sorption measurements and Transmission Electron Microscopy (TEM). The nature of silver species in these catalysts was investigated by XPS measurements, high angle XRD, high resolution TEM and TPR/H-2 (temperature-programmed reduction). The resulting materials were tested in the selective catalytic reduction of NO, by ethanol in the presence of oxygen. Finally, the effect of H-2 on the DeNO(x) activity was also investigated. The impregnation method of Al-SBA-15 by silver nitrate influences the size, the location of the particles and the catalytic activity. To maintain a higher DeNO(x) activity, the percentage of aluminium loading and the feed of H-2 gases should be increased. (C) 2009 Elsevier B.V. All rights reserved.