The catalytic activities of palladium-supported Sr0.8La0.2MnAl11O19 (SLMA) and the effect of phase transformation of palladium on the catalytic activity after high temperature treatments were studied by XRD, TPD, temperature programmed reaction (TPRX) and temperature programmed reoxidation (TPRO). Also the interaction of palladium with Sr0.8La0.2MnAl11O19 at high temperature was studied by XPS. PdO formed on Sr0.8La0.2MnAl11O19 was dissociated to metallic I'd after calcination at 1000degreesC. TPD and TPRX study revealed that the surface oxygen of PdO cluster was the major source of oxygen to react with CH4 in the absence of O-2. TPRO after TPRX experiments showed the reoxidation of catalysts was dependent on the calcination temperature. High temperature treatments caused the interaction of palladium and Sr0.8La0.2MnAl11O19 support resulting in the change of the oxidation state of palladium. (C) 2002 Elsevier Science B.V. All rights reserved.