Atmospheric Pressure Discharges have attracted much interest in recent years. The development of a new processes based on this discharge needs a clear understanding of plasma and discharge physics and chemistry. At the present time much attention is paid to the chemical processes in barrier discharge plasma in various gas mixtures, since the understanding of these processes is necessary for the development of industrial reactors. Besides these, hydrocarbons are being used for the formation of diamond like or amorphous carbon (DLC) films. Specially, hydrogenated amorphous carbon (a-C: H) and plasma polymerization. In this book we have used Dielectric Barrier Discharge (DBD) a plasma device used to investigate simple hydrocarbon reactions in a plasma phase. And deposition of thin films using gas mixtures C2Hm/Ar and C2Hm/N2 where, m = 2, 4, 6. The properties of the films have been presented with various characterizations.