The reaction mechanism of the reduction of NO by propene over Pd-based catalysts was studied by FTIR spectroscopy. It was observed that the reaction between NO and propene most probably goes via isocyanate (2256-2230 cm(-1)), nitrate (1310-1250 cm(-1)) and acetate (1560 and 1460 cm(-1)) intermediates formation. Other possible intermediates such as partially oxidized hydrocarbons, NO2, and formates were also detected. The reaction between nitrates and acetates or carbonates reduced nitrates to N-2 and oxidized carbon compounds to CO2. In situ DRIFT provides quick and rather easily elucidated data from adsorbed compounds and reaction intermediates on the catalyst surface. The activity experiments were carried out to find out the possible reaction mechanism and furthermore the kinetic equation for NO reduction by propene.