Barium-promoted　zirconia　(Ba-ZrO2)　was　synthesized　by　the　citric　acid　method　and　used　as　supports　for　Ru/Ba-ZrO2　catalysts,　which　were　prepared　by　incipient　wetness　impregnation　with　K2RuO　4　as　precursor.　The　obtained　Ba-ZrO2　and　catalysts　were　characterized　by　X-ray　diffraction　and　CO2　temperature-programmed　desorption.　The　effect　of　Ba　content　on　the　structure　and　catalytic　activity　of　K-Ru/Ba-ZrO2　catalysts　is　discussed.　The　formation　of　BaZrO　3　can　improve　significantly　the　catalytic　activity　of　Ru/Ba-ZrO　2　for　ammonia　synthesis.　The　ammonia　concentration　and　rate　of　ammonia　synthesis　of　the　K-Ru/Ba-ZrO2　catalyst　(molar　ratio　of　Ba:　Zr　is　1:1)　were　9.24　and　29.77　mmol/(g·h),　respectively,　at　425°C,　5.0　MPa,　and　10000　h-1.　Improvements　in　electron　conductivity　and　the　basic　nature　of　the　catalyst　may　be　the　main　reasons　for　such　high　catalytic　activity　in　ammonia　synthesis.　©　2012　Dalian　Institute　of　Chemical　Physics,　the　Chinese　Academy　of　Sciences.