In this study, La, Ce, or Y has been successfully incorporated into the γ-Al 2 O 3 framework to improve the Pt dispersion. Moreover, La and Y formed a dispersed phase, while a large portion of Ce constituted a separate phase on the Al 2 O 3 support in the form of CeO 2 . The formation and stability of the Pt–Sn alloy in the catalysts were remarkably influenced by the addition of La, Ce, or Y. Compared to pure Al 2 O 3 supports, La-doped Al 2 O 3 promoted the formation of PtSn, while Ce- and Y-doped Al 2 O 3 promoted the formation of PtSn 2 alloy on reduced catalysts. However, the stability of Pt–Sn alloy during the reaction exhibited different tolerances according to the catalyst used. Compared to those of the Pt–Sn/Al and Pt–Sn/Y–Al catalysts, Pt–Sn/La–Al and Pt–Sn/Ce–Al catalysts showed superior catalytic performances and stabilities because of the lower coke contents, higher stabilities of PtSn and PtSn 2 alloys, and smaller losses of Pt dispersion. This study suggests that the type and stability of Pt–Sn alloy formed on the Pt–Sn/support catalyst, which determined the catalytic performance and stability, were remarkably influenced by the support.