Several catalytic aftertreatment technologies rely on the conversion of NO to NO 2 to achieve efficient reduction of NO x and particulates in diesel exhaust. These technologies include the use of selective catalytic reduction of NO x with hydrocarbons, NO x adsorption, and continuously regenerated particulate trapping. These technologies require low sulfur fuel because the catalyst component that is active in converting NO to NO 2 is also active in converting SO 2 to SO 3 . The SO 3 leads to increase in particulates and/or poison active sites on the catalyst. A non-thermal plasma can be used for the selective partial oxidation of NO to NO 2 in the gas-phase under diesel engine exhaust conditions. This paper discusses how a non-thermal plasma can efficiently oxidize NO to NO 2 without oxidizing SO 2 to SO 3 .