The hydrocarbons present in diesel exhaust, although treated as minor pollutants, are equivalent to some of the major pollutants in terms of toxicity, contamination and harmfulness to the environment and hence, any effort towards treating hydrocarbons is a welcome step before letting the same into the atmosphere. In this current work two non-thermal plasma techniques viz., electrical discharge plasma (direct plasma) and ozone injection (indirect plasma) were coupled while treating the diesel exhaust for possible mitigation of total hydrocarbons (THC). The work is intended to provide a cleaning system which is non-catalytic, non-adsorbent and non-thermal plasma based one leading to less utilization of electrical energy and long lasting. The study was conducted at laboratory level with controlled flow conditions of the diesel exhaust. It was observed that the combined discharge plasma and ozone injection has resulted in more of THC reduction/conversion to the tune of 95% at about plasma specific energy of 55J/L and with an injection of 1656ppm of ozone. The individual as well as cascaded treatment techniques are discussed in detail and a comparative analysis of the same has been provided.