XANES and Raman reveal new information on the properties of supported Pt Sn nanoparticles during propane dehydrogenation–regeneration cycles leading to insight into the dynamics of Pt Sn alloy formation at elevated temperatures. The catalytic performances of Pt/Al 2O 3 and Pt–Sn/Al 2O 3 catalysts for the dehydrogenation of propane through consecutive reaction–regeneration cycles have been studied under realistic reaction conditions. A 10-fold successive dehydrogenation–regeneration cycling study, similar to that employed in an industrial propane dehydrogenation reactor, was performed in order to examine the catalyst activity and stability as well as the propene selectivity. Combined in situ UV–Vis/Raman spectroscopy measurements were taken in order to follow the coke formation processes during propane dehydrogenation. This approach allowed correlating propane conversion and propene formation with the on-line determined Raman D over G band intensity ratio and amount of coke formed. These in situ measurements on coke formation and related catalyst deactivation were supplemented by in situ high-energy resolution fluorescence detected (HERFD) XANES measurements in order to characterize the structural and electronic properties of the supported Pt and Pt Sn nanoparticles during the successive dehydrogenation–regeneration cycles. This combination of powerful spectroscopic techniques revealed unique information regarding the activity behavior and deactivation mechanism of Pt- and Pt Sn-based propane dehydrogenation catalysts, enabling us to identify important structure-electronic-performance relationships as well as fundamental insight into the dynamics of Pt Sn alloy formation processes in Pt nanoparticles at elevated temperatures.