In this study, a non‐thermal plasma reactor under atmospheric pressure instead of the usual catalytic processes was developed to produce synthesis‐gas (CO, H2) “syngas” from the CH4O2Ar system. Moreover, using the Gibbs free energy minimization method, the gas phase composition of plasma species was calculated as quantitative pre‐estimate for our analytical observations. In our experimental investigation, a plasma reactor consisting of a microwave plasma torch, gas tube, cooling section, and sampling part was used. The experiments have been carried out under atmospheric pressure with maximum 300 W microwave power. To analyze the produced gas, the gas chromatography (GC) and the Fourier transform infrared (FTIR) spectroscopy have been used. In order to optimize the production conditions, the effect of O2/CH4 gas flow rate and plasma power in the plasma chemistry phenomenon, CH4 conversion and CO selectivity have been investigated. Our experimental results confirm our simulations and they are in good agreement with existing literature data so far.