A gliding arc reformer was proposed to produce hydrogen-rich gas. The reformer has two reactors including a plasma reactor and a catalyst reactor. The reforming characteristics for each of the following variables were studied: O-2/C ratio, total gas flow rate, catalyst reactor temperature, reformer energy density, catalytic effect and CO2 input concentration to simulate biogas. Optimum conditions for producing H-2 from methane were also suggested. The conditions consisted of an O-2/C ratio of 0.64, a total gas flow rate of 14.2 L/min, a catalyst reactor temperature of 672 degrees C, a reformer energy density of 1.1 kJ/L and a steam flow ratio of 0.8. The maximum H2 concentration of 41.1% was obtained under the optimum conditions. Also, methane conversion rate, H2 yield and reformer thermal efficiencies were 67%, 54% and 35%, respectively. Crown Copyright (c) 2008 Published by Elsevier Ltd. All rights reserved.