Cu-Na-ZSM-5 catalysts were prepared by a dry technique from physical mixtures of Na-ZSM-5 with copper compounds (CuCl, Cu(NO3)(2) Or Cu(CH3COO)(2)) in order to obtain intrazeolite copper species coexisting with the full amount of Na+ ions of the parent zeolite, For this purpose, the parent mixtures were heated in inert gas or vacuum to 823-873 K., The transport of copper into the near-surface regions of the zeolite crystals was monitored by surface-analytical techniques (XPS, X-ray induced AES), into the bulk of the crystals by infrared spectroscopy of adsorbed pyridine, It was found that the chemical transport is most intense for copper associated with chlorine, but intrazeolite copper can be stabilized also in chlorine-free systems, When H-ZSM-5 is available together with Na-ZSM-5, solid-state ion exchange into the former predominates over chemical transport into the latter. The activity of these samples for the selective catalytic reduction of NO by propene was investigated in a broad temperature range and compared with the activity of reference catalysts prepared by aqueous exchange, which exhibited Bronsted acidity, Reaction rates normalized to the copper content were in the same order of magnitude for both types of Cu-ZSM-5 samples, which demonstrates the irrelevance of Bronsted acidity for the SCR by propene over Cu-ZSM-5., On the basis of surface-analytical data and trends in the temperature dependence of the activity, it was suggested that both isolated copper ions and intrazeolite but extralattice copper oxide clusters provide active sites for the SCR reaction.