Abstract In the presence of a copper phthalocyanine complex (CuPc) it is possible to synthesize ZSM-5 zeolite containing the complex, and the crystallinity is good provided the amount of CuPc trapped is much lower than the number of channel intersections where it can be located without too much distortion. The crystallinity is retained after decomposition of the CuPc in a stream of air at 500°C. The copper-ZSM-5 system is characterized by the combined application of xenon adsorption, ESR and 129Xe NMR spectroscopy. These techniques allow the location and the oxidation states of the copper ions after various thermal treatments to be studied. 129Xe NMR gives evidence about the partial self-reduction of the Cu 2+ ions during the dehydration process. The ESR spectra taken after adsorption of ammonia or o-xylene confirm that the Cu 2+ ions are located in the channels. However, the NMR spectroscopy of adsorbed xenon shows that when there is no chemisorbed phase the Cu 2+ are stabilized in the crystallites but outside the channels. They return to the channels upon chemisorption of ammonia.