Fe(III)-modified　clinoptilolites　(Fe-CPs)　were　prepared　by　hydrothermal　treatment.　The　collapse　of　the　heulandite　skeletons　was　avoided　by　adjusting　the　pH　value　using　HCl　solution,　showing　the　maximum　relative　crystallinity　of　the　Fe-CPs　at　an　optimal　pH　of　1.3.　The　competitive　exchange　performances　between　Fe3+　ions　and　H+　with　Na+　(and　K+)　suggested　that　the　exchange　sites　were　more　easily　occupied　by　H+.　Various　characterizations　verified　that　the　hydrothermal　treatments　had　a　strong　influence　on　the　dispersion　and　morphology　of　the　isolated　and　clustered　Fe　species.　The　high　catalytic　activity　of　the　oxygen　evolution　reaction　indicated　the　insertion　of　Fe3+　into　the　skeletons　and　the　occurrences　of　isomorphic　substitution.　The　fractal　evolutions　revealed　that　hydrothermal　treatments　with　the　increase　of　Fe　content　strongly　affected　the　morphologies　of　Fe　species　with　rough　and　disordered　surfaces.　Meanwhile,　the　Fe(III)-modified　performances　of　the　CPs　were　systematically　investigated,　showing　that　the　maximum　Fe-exchange　capacity　was　up　to　10.6　mg/g.　Their　thermodynamic　parameters　and　kinetic　performances　suggested　that　the　Fe(III)-modified　procedures　belonged　to　spontaneous,　endothermic,　and　entropy-increasing　behaviors.　Finally,　their　adsorption　capacities　of　CO2　at　273　and　298　K　were　preliminarily　evaluated,　showing　high　CO2　adsorption　capacity　(up　to　1.67　mmol/g　at　273　K).　©　2023　by　the　authors.