Plasma-assisted catalysis technology has been identified as one of the most efficient feasible routes for DeNO(x). In this work, a combined NOx adsorption-CH4 plasma discharge process has been developed for DeNO(x). The conversion of the adsorbed NOx on H-MOR and Co-MOR could reach 99.7% and 98.3% in the present process at ambient temperature, respectively. The results verified the feasibility of the present process using MORs as adsorbents and catalysts in theory. Then, the cost-effective natural mordenite (NMOR) was used as the adsorbent and catalyst instead of MOR. After acid treatment and ion-exchange, the modified Co-NMOR exhibited higher NOx adsorption capacity than MOR. The NOx conversion and N-2 selectivity on Co-NMOR were 95.0% and 100.0% in the CH4-plasma discharge stage, respectively. Meanwhile, the cyclic operation of Co-NMOR for DeNO(x) has also been investigated.