Pd/HZSM-5 catalysts prepared via glow discharge plasma reduction followed by calcination thermally show excellent enhanced stability for methane combustion. EXAFS characterization confirms that argon glow discharge reduces Pd/HZSM-5 catalyst effectively at close to room temperature. After thermal calcination of argon plasma reduced Pd/HZSM-5 catalyst under air, specific tetragonal PdO species are formed. This kind of active PdO species keeps stable during methane combustion, which leads to the observed excellent stability of plasma prepared Pd/HZSM-5 catalyst. EXAFS characterization also shows argon plasma reduction can help to remove Cl, which has a negative effect on catalysts properties. (c) 2007 Elsevier B.V. All rights reserved.