MCM-22 zeolites with different Si/Al ratios were dynamically synthesized through hydrothermal method, and the Pd/MCM-22 catalysts were prepared by ion-exchange method as well. The physicochemical properties of the samples were well characterized by XRD, SEM, TEM, N-2 adsorption, NH3-TPD, and FT-IR of d(3)-acetonitrile adsorption. MCM-22 synthesized was markedly different from those in previous literatures, showing much smaller crystals. MCM-22 with Si/Al ratio of 25 showed the highest crystallinity and concentration of Bronsted acid sites. The loading of Pd particles had little influence on the structural and porous properties of MCM-22 zeolite. The specific surface area, pore volume, pore diameter, and the concentrations of the acid sites all decreased with increasing Pd loading as expected. One-step synthesis of methyl isobutyl ketone from acetone was investigated over Pd/MCM-22 catalysts. An acetone conversion of 34.0% and a selectivity of 86.9% for MIBK were realized. The catalytic results also suggested that a proper balance between metallic and acidic sites was necessary for obtaining high catalytic performance. (c) 2007 Elsevier B.V. All rights reserved.