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/Ce0　5Zr0　5O2　catalyst　prepared　by　adsorbing　Pd　nanoparticles　on　Ce0　5Zr0　5O2　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