The laboratory-scale behaviour of a methane-air Mixture injected at atmospheric pressure and ambient temperature into a non-thermal plasma (NTP) reactor is investigated experimentally and numerically as a function of CH4 concentration and mass flow rate. Numerical simulations of the NTP reactor gas phase are performed with a chemical kinetic model used initially for CH4 oxidation in a perfectly stirred reactor (PSR). The computed H-2, CO, CO2 and remaining CH4 mole fractions are in good agreement with e experimental data. Syngas (H-2 and CO) production from CH4-air mixture is demonstrated over a large range of fuel flow rates and methane amounts in air. The lowest energy cost of H-2 production is about 45 kWh/kg((H2)) for the highest mass flow rate. Numerical simulation has confirmed that the optimum use of electrical power by the NTP reactor is achieved for high mass flow rates and low inlet CH4 concentration in air. (C) 2008 Elsevier B.V. All rights reserved.