The transformation of a model mixture of a diesel exhaust (1000 ppm NO, 670 ppm propene, 10% O-2, 10% H2O - total flow rate of 50000 l l(-1) of catalyst per hour) was investigated over a Cu-MFI catalyst prepared by complete exchange of the sodium ions of a NaMFI sample (Si/Al=27) by Cu2+. IR study of pyridine adsorption on this catalyst shows the presence of a significant amount of strong protonic acid sites resulting from the hydrolysis of the Cu2+ cations. The amount and the composition of the carbonaceous compounds ("coke") retained in the pores from 130 degrees C to 350 degrees C were determined. Reaction steps over the oxidation and the acid sites are proposed to explain the formation of the main coke components : carbonylated and furanic compounds, isoxazoles and nitriles. Formation of nitrogen could result to a small extent from a complete oxidation of nitrile intermediates and to a larger extent from reaction between nitrile and NO2.