In this paper, plasma treatment of Ni catalyst for partial oxidation of methane to syngas was investigated by using plate-plate discharge model via a corona discharge by flowing argon under atmospheric pressure and room temperature. The catalytic activity and stability for partial oxidation of methane (POM) process were measured for the catalyst before and after plasma treatment. It was found that after plasma treatment, methane conversion increased 5-10% and the syngas selectivity kept the same as before treatment. Also, these catalysts were characterized by thermogravimetric analysis and XPS measurement. It was found that the argon plasma treatment can improve the catalytic stability by preventing the carbon deposition on the Ni catalyst. (C) 2003 Elsevier B.V. All rights reserved.