The influence of feed gases proportion on the performance of gliding arc discharge (GAD) plasma assisted methane reforming with carbon dioxide process (DMR) is investigated, especially focused on the reagents conversion, the main by-product distribution and the energy consumption. An additional analysis of the theoretical conditions of equilibrium and its comparison with the experimental results are also included. The GAD assisted DMR process is effective in converting CH4/CO2 into synthesis gas with C2H2 and C2H4 detected as the main hydrocarbon compounds. Strong dehydrogenation in the GAD assisted DMR process is suggested with no obvious C2H6 observed in the effluent and serious coke formation and deposition detected in the relative high CH4/CO2 feed ration and supply voltage condition. Compared to other plasma systems reported before, the GAD reactor used in current work shows lower energy consumption for methane conversion but higher energy consumption for C2H2 formation. The increase of CH4/CO2 molar ratio in the feed gases favors the reagents conversion and consequently promotes the formation of each by product. Meanwhile, the by-product selectivities, the value of H-2/CO ratio in the effluent, the coke formation, and the special energy consumption for reagents conversion and synthesis gas formation are shifted. It is clearly demonstrated that under some certain circumstances, the GAD plasma reactor assisted reaction can be totally out of thermodynamic equilibrium. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.