Ceria　(CeO2)　supports　are　unique　in　their　ability　to　trap　ionic　platinum　(Pt),　providing　exceptional　stability　for　isolated　single　atoms　of　Pt.　The　reactivity　and　stability　of　single-atom　Pt　species　was　explored　for　the　industrially　important　light　alkane　dehydrogenation　reaction.　The　single-atom　Pt/CeO2　catalysts　are　stable　during　propane　dehydrogenation,　but　are　not　selective　for　propylene.　DFT　calculations　show　strong　adsorption　of　the　olefin　produced,　leading　to　further　unwanted　reactions.　In　contrast,　when　tin　(Sn)　is　added　to　CeO2,　the　single-atom　Pt　catalyst　undergoes　an　activation　phase　where　it　transforms　into　Pt-Sn　clusters　under　reaction　conditions.　Formation　of　small　Pt-Sn　clusters　allows　the　catalyst　to　achieve　high　selectivity　towards　propylene　because　of　facile　desorption　of　the　product.　The　CeO2-supported　Pt-Sn　clusters　are　very　stable,　even　during　extended　reaction　at　680　degrees　C.　Coke　formation　is　almost　completely　suppressed　by　adding　water　vapor　to　the　feed.　Furthermore,　upon　oxidation　the　Pt-Sn　clusters　readily　revert　to　the　atomically　dispersed　species　on　CeO2,　making　Pt-Sn/CeO2　a　fully　regenerable　catalyst.