This study demonstrates a noncatalytic, low-pressure, and room-temperature process for methane partial oxidation into syngas by using a microwave plasma torch reactor. The experimental results showed that the elevation of the inlet O-2/CH4 molar ratio, pressure, and applied power led to the outlet H-2/CO molar ratios decreased from 3.32 (at O-2/CH4 = 0.3, 13.3 kPa, and 160 W) to 0.81 (at O-2/CH4 = 1.5, 93.3 kPa, and 600 W). At O-2/CH4 = 0.5, the higher selectivity and yield of syngas, and a H-2/CO molar ratio of about 2 could be obtained simultaneously. In addition, the maximum yield of syngas per unit mole of methane consumed could be achieved at a higher pressure, although a higher methane conversion was performed at a lower pressure. Based on these, this study suggests that the operating conditions of O-2/CH4 = 0.5 and near atmospheric pressure (93.3 kPa) would be the most appropriate combination for converting methane into syngas. Under the conditions, the selectivities of H-2 and CO reached 97.6 and 99.2%, respectively, accompanied with H-2/CO = 1.97 at 600 W. (c) 2005 American Institute of Chemical Engineers.