A series of copper-exchanged ZSM-5 samples of various copper contents were prepared. In freshly prepared Cu/ZSM-5, there is surface enrichment in copper, especially for the over-exchanged samples. This enrichment diminishes after heat treatments such as calcination or treatment in an inert gas. The oxidation state of copper can be easily altered. The introduction of nickel into over-exchanged Cu/ZSM-5 did not improve the activity. However, the activity of under-exchanged Cu/ZSM-5 slightly improved in the presence of the second metal.