An experimental investigation has been conducted to reduce NOxfrom combustion flue gases by means of corona discharge activated methane radical injection methods. Two types of corona radical injectors, the hollow needle type and the multihole type, are used in the present investigations. Experiments are conducted for the simulated flue gas (Nx:Ox:COxNO = 83.996:8:8:0.004) flow rate from I to 20L/min., the activation voltage from 0 to 40 KV and the Ar-methane mixture gas (95:5) flow rate from 0 to 200 mL/min. The results show that the NOxreduction increases with increasing activation voltage and nonmonotonically depends on methane stoichiometry. Trace amounts of N2O and NH3were observed as a by product