The　electronegativity　of　Li　is　much　higher　than　that　of　Na　or　K,　but　the　ammonia　synthesis　activities　of　Li-promoted　Ru/AC　catalysts　were　comparable　to　the　values　of　Ru　catalyst　promoted　with　K,　which　were　much　higher　than　those　over　Ru　catalyst　with　Na　promoter.　The　presence　of　Li　increased　the　catalytic　activity　by　changing　the　chemisorption　properties　such　as　hydrogen　adsorption　and　nitrogen　adsorption　for　carbon-supported　Ru　catalysts,　rather　than　affecting　the　sizes　of　Ru　particles　or　the　electron　density　of　Ru　metal.　(C)　2013　Elsevier　B.V.　All　rights　reserved.