Effects of carbon dioxide (CO2) addition and pulsed gliding arc (PGA) plasma on methane (CH4) flame stability and pollutant emissions are investigated in this paper. Two main parts are reported: the effects of CO2 addition to the fuel and the impact of PGA plasma on the characteristics of non-premixed CH4/CO2-air flames in a coaxial swirl burner. The burner consists of 2 concentric tubes, the central tube supplies the CH4 flow and the periphery one supplies the airflow. In the central tube, a metal rod is used as a cathode. To produce the PGA plasma, two other electrodes are symmetrically placed around the central one to obtain two PGA plasma zones in the stabilization area of flame. The combustor is a parallelepiped chamber, with a 0.48 m square cross section and 1 m height equipped with six windows on each side. This work primarily focuses on pollutant emissions (NOx and CO), flame structures, and stability. OH* chemiluminescence measurements are used to describe the structure and stability of the flame providing information on the flame lengths and lift-off heights. The lift-off heights and the flame lengths are determined as a function of the CO2 concentrations, ranging from 0% to 50% in the fuel, at a fixed swirl number and equivalence ratio. The results show that CO2 addition to the fuel changes significantly the flame shape and its behavior. The flame becomes more unstable at high CO2 percentages. CO2 addition dilutes reactants, reduces NOx production, and increases CO concentrations in the flue gases. To overcome the instabilities problems due to the addition of CO2, the PGA is used and investigated with different parameters of plasma and flame. PGA plasma is generated by a DC pulsed power generator with HV pulse duration of few microseconds. It is observed that the presence of PGA plasma decreases flame instabilities and reduces CO concentration in the flue gases.