The effect of a non-thermal plasma reactor over a commercial Diesel oxidation catalyst (DOC) was investigated. Studies have been focused on the gas treatment efficiency together with lowering light-off temperature when a DOC catalyst was connected downstream to plasma reactor in test bench scale. Experiments have been conducted using multi-DBDs (dielectric barrier discharge) reactor in planar configuration driven by a HV AC generator (11 kV-15 kHz). The specific input energy was set to 57 and 85 J/L. Experiments were performed in gas composition simulating Diesel exhaust. Commercial DOC, monolith-supported Pt-Pd/Al2O3, was used at gas hourly space velocities of about 55,000 and 82,000 h-1. CO and hydrocarbons light-off curves were determined for DOC, plasma, and plasma-DOC systems by temperature programmed surface reaction from 80 to 400° C. Particular attention has been paid to the gas temperature between the plasma reactor and the DOC. Results show that the plasma-catalyst system provides the lowest light-off températures for CO and HCs. Under conditions of this study, light-off temperature improvement by about 57° C was obtained and the plasma reactor totally oxidized NO to NO2 at low temperature.