A Cu/mordenite catalyst was prepared by ion exchange and characterized by N-2 sorption, XRD, TPR by H-2 and TPD by NO. The catalyst was evaluated in the selective catalytic reduction of NO by decane in O-2-rich atmosphere under temperature-programmed reaction from 293 to 773 K. Two NO reduction profiles at 590 and 650 K occur under these conditions. By testing different operating protocols and different alkanes as reductants, it was concluded that the low temperature peak (590 K) is due to alkane condensed in the porosity of mordenite.