Methylcyclohexane (MCH) is a prospective hydrogen carrier candidate. Although Pt/Al2O3 catalyst shows high conversion for dehydrogenation of MCH at 623 K, methane formation and deactivation caused by coke deposition are issues over the catalyst. Results of this study demonstrate that Mn addition to Pt/Al2O3 brought higher selectivity and stability for dehydrogenation of MCH than with Pt/Al2O3 alone. Although Pt and Mn do not form an alloy structure, Pt and Mn form an adjacent structure, and the unsaturated coordination of Pt which promotes methane formation and deactivation decreased. Pt-Mn/Al2O3 shows high catalytic performance by virtue of the coverage of such sites by MnOx.