The　grafting　reaction　of　SnMe4　onto　the　supercages　of　HY　zeolite　was　studied　under　high　vacuum　condition,　and　the　chemical　composition　and　structure　of　resulting　solid　were　characterized　by　in　situ　FT-IR,　XRD,　UV-Vis,　DRS,　DTG,　DTA,　N-2　adsorption,　ICP,　elemental　analysis,　and　gas　chromatography.　The　reaction　could　occur　rapidly　and　quantitatively　at　low　temperature　down　to　188　K　(apparent　active　energy　was　10.4　kJ(.)mol(-1)),　resulting　in　the　grafting　of　well-defined　-Sn(CH3)(3)　fragments　onto　the　surface　of　zeolite　supercages.　The　grafted　Y　zeolite　is　quite　different　from　the　starting　HY　zeolite　in　adsorption　properties,　and　showed　obvious　size-selectivity　for　hydrocarbons.