Cinnamaldehyde hydrogenation behaviors of platinum nanosheets intercalated between graphite layers (Pt-GIC) were studied and compared with those of platinum particles on graphite surface (Pt/Gmix) in supercritical carbon dioxide solvent at 323 K. The conversions of cinnamaldehyde of PtGIC were lower than those of Pt/Gmix; however, the cinnamyl alcohol yields were higher than those of Pt/Gmix at similar conversions. Carbon dioxide solvent would carry hydrogen and cinnamaldehyde molecules to the edge sites of platinum nanosheets located between graphite layers, which are selective sites for the cinnamyl alcohol production.