Copper ion-exchanged solids prepared by the modified sol-gel method with different percentage of the organic and inorganic silicoaluminate, and with a 25% of zeolite ZSM-5, were studied as catalysts for the selective catalytic reduction of NO by propene in the presence of oxygen and water. The solids without zeolite were active for this reaction, but showed a poor performance under wet conditions. The addition of the zeolite to obtain a mixed solid strongly enhanced the NO conversion. The deactivation by water is lower and fully reversible. © 2006 Elsevier B.V. All rights reserved.