Two-dimensional radio-frequency methane plasma simulation, have bren carried out. The simulations consider discharge physics, eas phase chemistry, and surface deposition. The objectives of the study are to provide insights to species dynamics and investigate their effects on the deposition process for a polyatomic depositing gas discharge under the operating conditions of an experimental reactor. The model predictions of the electron density profile and self-generated dc bias compare well with the experimental results. The temporal and spatial variations of plasma variables are also obtained for real reactor operating condition. The gas phase chemistry and surface deposition model predictions of the axial variations of CH2 and CH3 radical densities are also compared with experimental data. The CH2 and CH3 radicals and positive ion fluxes to the cathode are used for the prediction of the carbon thin film deposition rate on the wafer.