The　reaction　of　ferrocene　with　the　acidic　hydroxy　groups　in　the　supercages　of　zeolite　HY　dehydrated　at　673　K　and　the　reactivity　of　the　resultant　surface　species　towards　CO　and　O-2　were　investigated　by　temperature-programmed　decomposition　(TPD)　and　reduction　(TPR)　and　IR,　X-ray　absorption　fine　structure　analysis　(XAFS),　and　X-ray　photoelectron　(XP)　spectroscopy.　In　situ　FTIR,　TPD,　TPR.　and　chemical　analysis　reveal　that　the　Cp2Fe　molecule　adsorbed　on　the　zeolite　surface　loses　one　cyclopentadienyl　group　under　vacuum　at　423　K,　which　leads　to　the　formation　of　a　well-defined　mononuclear　surface　Fe-C5H6　complex　grafted　to　two　acidic　sites　and　one　(equivalent　to　Si-O-Si　equivalent　to)　unit,　as　confirmed　by　the　lack　of　Fe-Fe　contributions　in　the　EXAFS　spectra.　Each　iron　atom　is　coordinated,　on　average,　to　three　oxygen　atoms　of　the　zeolite　surface　with　a　Fe-O　distance　of　2.00　angstrom　and　to　five　carbon　atoms　with　a　Fe-C　distance　of　2.09　angstrom.　IR　spectra　indicate　that　the　cyclopentadiene-iron　species　grafted　on　the　surface　of　the　zeolite　is　quite　stable　in　vacuo　or　under　an　inert　or　hydrogen　atmosphere　below　423　K,　and　is　also　relatively　stable　under　oxygen　at　room　temperature.　However,　the　cyclopentadiene　ligand　readily　reacts　with　CO　to　form　a　compound　containing　carbonyl　at　323　K,　and　even　at　room　temperature.　The　single　carbonyl　band　in　the　IR　spectra　provides　evidence　for　the　nearly　uniform　formation　of　a　cyclopentadiene-iron　species　on　the　surface　of　the　zeolite.