Catalysts prepared by supporting tin and platinum in the potassium form of L-zeolite exhibit high activity and selectivity for isobutane dehydrogenation and resistance to deactivation at 673-773 K. Mossbauer spectroscopic results show that some of the tin interacts with platinum to form Pt/Sn alloy particles in reduced Pt/Sn/K-L catalysts, while the remainder of the tin is present as Sn2+. Potassium displaced by Sn2+ from ion-exchange positions in the zeolite may interact with Pt/Sn particles in the catalyst. The addition of excess potassium to Pt/Sn/K-L catalysts further enhances the dehydrogenation activity and selectivity. It is suggested that tin and potassium in Pt/Sn/K-L decrease the size of the surface platinum ensembles, thereby inhibiting isomerization and hydrogenolysis reactions of isobutane, The high activity for isobutane dehydrogenation over Pt/Sn/K-L catalysts may be attributed to stabilization of molecularly adsorbed isobutane species by the zeolite pore structure and/or by excess potassium, which enhances the rate limiting dissociation of isobutane.