Reaction kinetics deal with the time evolution of the chemical reactions. Generally, usually not the full mechanism, which quantitatively describes the process, is really interesting but the set of those reaction steps that explain the process and its essence. The reduction of the reaction mechanism and its kinetic analysis would help us to describe and treat scientifically and environmentally important chemical problems such as chemical processes in industrial and natural plasma. In order to get knowledge about the chemical background of the generation of the products formed in methane plasma, in this work reaction kinetic simulations were carried out for methane-argon system. Moreover, the reactions in the atmospheres of the Titan and the early Earth initiated by lightning were also modeled with kinetic simulations. The decomposition of a 'model material' of the perhalogenated hydrocarbons, which have important role in the stratospheric ozone depletion, the carbon tetrachloride was also modeled both in inert and in oxidative environments. This book is suitable for ones who deal with chemical processes in lightning or in industrial plasma and also for physico-chemists in general.