The methane combustion behavior is investigated over Pd catalysts supported on Ce-Zr/Al2O3 and Ce-Zr-M/Al2O3 (M=Mg, Ca, Sr, Ba). Characterization of the catalysts is performed by BET, XRD, TEM, H-2-TPR, O-2-TPO and CH4/O-2-TPSR techniques. Activity tests in methane combustion show that the addition of trace alkaline earths to Pd/Ce-Zr/Al2O3 catalyst obviously increases the catalytic activity of the catalysts under lower reaction temperature conditions, and Pd/Ce-Zr-Ca/Al2O3 exhibits the highest catalytic activity and thermal stability among all catalysts. The addition of Ca to Pd/Ce-Zr/Al2O3 inhibits the site growth and decomposition of PdO particles and improves the reduction-reoxidation properties of the active PdO species, which increases the catalytic activity and thermal stability of the Pd/Ce-Zr/Al2O3 catalyst. (c) 2005 Elsevier B.V. All rights reserved.