The　bimetallic　Pt-Sn　catalysts　are　known　to　be　the　most　efficient　ones　for　propane　dehydrogenation　reaction;　however,　the　synthesis　of　bimetallic　Pt-Sn　nanocluster　(below　1　nm)　with　an　alloy　structure　still　remains　a　formidable　challenge.　An　approach　for　the　controllable　synthesis　of　Pt-Sn　nanocluster　based　on　Surface　Organometallic　Chemistry　on　oxide　concept　is　developed　here,　which　involves　two　basic　steps:　the　sequential　grafting　of　Pt(COD)Me-2　and　HSnPh3　at　the　surface　of　dehydroxylated　theta-Al2O　leading　to　the　formation　of　well-defined　bimetallic　surface　compound　consisting　of　[(　AlO-)Pt(COD)Me]　and　[(=AlO-)SnPh3]　fragments,　and　the　hydrogenolysis　of　this　surface　compound　under　a　mild　condition　giving　rise　to　the　ultra-small　bimetallic　Pt-Sn　cluster　around　0.75　nm.　The　achieved　Pt-Sn/theta-Al2O3　catalysts　exhibit　high　activity,　selectivity　and　stability　in　propane　dehydrogenation　to　propylene.　(C)　2019　Elsevier　Inc.　All　rights　reserved.