The ultrasonic-assisted membrane reduction (UAMR) method was used to prepare colloidal Pd nanoparticles An orthogonal experiment was performed to investigate the effect of synthesis parameters in UAMR on NI particle size The average Pd particle size can be regulated in a wide range of 5-220 nm The fabrication of supported Pd catalyst from a typical nano-sized Pd colloid with 1 wt% Pd loading was studied The colloid and as-prepared catalyst were characterized by TEM, BET, ICP-OES, XRD, H(2)-TPR, and CO catalytic oxidation. Fabrication methods would have significant impacts on the actual Pd content, metal dispersion. PdO/Pd reducibility, textural property, etc over different supports The CO oxidation activity of the catalysts was consequently decided by these characters The Pd/Ce(0 5)Zr(0 5)O(2) catalyst prepared by adsorbing Pd nanoparticles on Ce(0 5)Zr(0 5)O(2) showed the highest activity with CO complete oxidation at 150 degrees C among all of the catalysts investigated (C) 2010 Elsevier B V All rights reserved