Application of radio-frequency (RF) plasma as an alternative technology for the decomposition of carbon dioxide with methane gas is demonstrated. The results of this study revealed that in CO2/CH4/Ar plasma, the best decomposition fraction of carbon dioxide was 60.0%, which occurs around 316 degrees C in the condition designed for 5% feeding concentration of CO2, 5% feeding concentration of CH4, 20 torr operation pressure, 100 seem total gas flow rate and 90 watts input power wattage. The CH, CH2 and CH3 radicals obtained from the destruction of CH4 could result effectively in high decomposition of CO2 in the plasma reactor. The optimal mathematical models based on the experimental data obtained were also developed and tested by means of sensitivity analysis, which shows that the input power wattage (W) was the most sensitive parameter for the CO2 decomposition. (C) 1998 Society of Chemical Industry.