With ever more stringent NOxemissions, it is necessary to examine removal of nitrogen oxide removal 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 design 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 tested individually for the treatment of nitrogen oxides for gas flow rate of 2 l/min, 5 l/min and 10 l/min. Both the reactors have been tested individually and results shows appreciable removal of NOxwith equal corona volume.