Methane conversion in the presence of carbon dioxide was investigated under the conditions of dielectric-barrier discharge plasmas. Different from the previous investigations, the grounded electrode is covered by the dielectric material (quartz) in the present reactor design. The product contains gaseous hydrocarbons, syngas and oxygenates. No liquid hydrocarbons can be detected with the present reactor design. The oxygenates produced includes acetic acid, propanoic acid, ethanol and methanol. There exists an optimum feed ratio of CH4/CO2 to make the maximum selectivity of the objective oxygenate. The highest selectivity of acetic acid was 5.2% achieved at CH4 and CO2 conversions of 64.3% and 43.1%, respectively. (C) 2003 Elsevier Science B.V. All rights reserved.