Abstract: The direct conversion of methane to acetylene and the indirect conversion of mathane to syngas were studied by using the atmospheric pressure spark discharge, and with the in-situ diagnosis of optical emission spectroscopy. The results were compared with the dielectric barrier discharge. Results show that, the spark discharge, having remarkable advantage of high energy efficiency, was able to easily activate the methane molecules into species such as C, H and C₂. C₂H₂ was formed as a major hydrocarbon product when methane was fed alone, while the syngas was formed with adjustable H₂/CO ratio when CO₂ and O₂ were co-fed with methane. It is worth of mention that, the addition of O₂ overcame completely the troublesome problem of reactor coking during the spark discharge of CH₄ and CO₂, the production of syngas was allowed to be carried out at a temperature as low as 225 ℃. Therefore, the new syngas preparation method is very attractive comparing with the traditional catalytic routes.