The structure and properties of Pd/WO3-ZrO2 (W/Zr=0.2) catalysts with different Pd loadings and precursors were investigated. The results indicate that Pd/WO3-ZrO2 prepared from a PdCl2 precursor was optimum for high activity and selectivity. Moreover, ethylene conversion increased with the Pd loading The structure and nature of the catalysts were characterized using X-ray diffraction, BET N-2 adsorption, H-2 temperature-programmed reduction and H-2 pulse adsorption techniques The results reveal that the higher catalytic performance of Pd/WO3-ZrO2 prepared from PdCl2 could be related to the formation of polytungstate species and the existence of well-dispersed Pd particles. (C) 2009 Elsevier B.V All rights reserved