The decomposition of naphthalene in surface dielectric barrier discharge (SDBD) based reactor is investigated in different carrier gases (air, nitrogen, and oxygen) in order to understand the reaction mechanism of the decomposition process. The decomposition efficiency of naphthalene is determined at different oxygen content (from 0 to 10 vol%) and different input power. The highest decomposition efficiency is obtained in nitrogen at low input power, due to the role played by the nitrogen excited species in the decomposition process. In addition, the decomposition efficiency is decreased with increasing the oxygen content at a low input power. At a relatively high input power, the decomposition efficiency reached its maximum value in pure oxygen. Moreover, the decomposition efficiency decreases with the increase of the oxygen content reaching minimum value at a small content of oxygen (similar to 3 vol% O-2) and relatively high input power, and then increases at higher oxygen content. The results show that the decomposition of naphthalene in the present reactor could be treated as a first order reaction with respect to the concentration of naphthalene.