Hydrogen production from methane-air mixtures using a two-stage cold electric discharge plasma reactor was experimentally investigated. Operating conditions, including voltage, frequency, and feed gas composition, were evaluated to determine the optimal conditions for maximizing methane conversion and hydrogen gas production. Experiments were carried out at ambient temperature and atmospheric pressure with reactant molar ratios (CH4:air) of 3:1, 2:1, 1:1, and 1:2 at specific energy inputs (SEI) of 20 and 60 J/mL. In the reactor outlet stream, H2, CO, CO2, and C2Hᵧ compounds were detected. Furthermore, the single-stage plasma system was compared with the two-stage system, showing an improvement in methane conversion and hydrogen selectivity using plasma in two stages. In a two-stage plasma system with an applied voltage of 60 kV and a total gas flow rate of 60 mL/min, a maximum hydrogen selectivity of 42 % was achieved. This paper aims to discharge plasma energy in two stages along the gas flow line to improve energy efficiency and hydrogen selectivity. The results showed that the two-stage plasma reactor had higher methane conversion (about 20 %) than the single-stage reactor. This improved performance is due to the presence of hydrogen in the second-stage plasma.
