With ever more stringent NOXemissions, it is necessary to examine removal of nitrogen oxide from diesel engine exhaust. This paper describes the study of NOXreduction from 5.9-kW stationary diesel engine exhaust under nanosecond pulse energization. Two plasma reactors characterized by dielectric barrier discharge has been designed, built, and evaluated. One of the reactor designs include nine numbers of electrodes kept in parallel, and the exhaust was allowed to pass axially, whereas the second reactor consists of nine parallel electrodes and the exhaust was allowed to pass radially. The reactors were individually tested for the treatment of nitrogen oxides for gas flow rate of 2, 5, and 10 L/min. Both the reactors have been individually tested, and results show an appreciable removal of NOXwith equal discharge volume. From the results, it was found that both the reactors were an efficient NOXremoval. With consumption of only 36 J/L, the reactors had shown a considerable 45% NOXefficiency.