A　series　of　Ag-Ru/CeO2　catalysts　were　prepared　by　conventional　impregnation　methods　and　characterized　by　XRD,　BET,　XPS,　H-2-TPR,　H-2-TPD-MS,　and　N-2-TPD.　The　activity　test　shows　that　ammonia　concentration　of　the　catalyst　with　6%　Ag　is　9.4%　at　10　MPa,　10,000　h(-1),　400　degrees　C,　which　is　22%　higher　than　that　of　Ru/CeO2.　Such　high　catalytic　activity　was　ascribed　to　three　effects:　electron　donating　property　of　partially　reduced　CeO2-x　to　Ru　metal,　the　low　workfunction　of　Ru　atoms　and　the　less　competitive　adsorbed　between　hydrogen　and　nitrogen　on　Ru　atoms　derived　from　the　synergetic　effect　between　Ag　and　Ru.　Crown　Copyright　(c)　2012　Published　by　Elsevier　B.V.　All　rights　reserved.