The synthesis of ammonia has been studied in methane-nitrogen plasmas using a micro-gap discharge under an environmentally friendly condition. The effects of some parameters such as the specific input energy, the discharge gap, the volume ratio of CH 4 / N 2 , the residence time, and the gas temperature on the yield of NH 3 and conversion rate of CH 4 are discussed in the paper. The results show that the highest yield of NH 3 is 8000 ppm for a residence time of 1.6 s. In addition, the yield and generating rate of H 2 are 9.1% (v/v) and 1879.8 lmol/min, respectively. Therefore, the micro-gap discharge is an efficient method for NH 3 synthesis and H 2 generation from CH 4.