A surface intermediate with a C/N ratio close to 3 has been shown by TPD to form at co-adsorption of NO and propane as well as NO, propane and O2 on low-exchanged Cu-ZSM-5. The adsorption of NO, propane and oxygen has been studied to evaluate their effect on the formation of this complex. Its formation is accompanied by a decrease in the concn. of surface nitrite-nitrate. The kinetics of nitrite-nitrate adspecies formation as a function of the reagents concn. and temp. has been investigated. Some NO adspecies have been found to decomp. yielding N2O.