The catalytic properties of H 2-reduced Pt/MoO 3 for the isomerization of pentane and heptane were compared to those of Pt/zeolites. H 2-reduced Pt/MoO 3 was more active for pentane isomerization than Pt/Hβ and Pt/USY. In contrast, the heptane isomerization activity decreased in the following order: Pt/Hβ>H 2-reduced Pt/MoO 3>Pt/USY. All of the catalysts gave negative kinetic orders toward hydrogen in both pentane and heptane isomerization. The reaction order toward pentane was positive in all cases. The reaction order toward heptane on H 2-reduced Pt/MoO 3 was found to be −0.3, whereas those on Pt/Hβ and Pt/USY were zero and positive, respectively. These results indicate that heptane was more strongly adsorbed on H 2-reduced Pt/MoO 3, resulting in the low heptane isomerization activity. Adsorption studies showed that interaction of heptane with the surface of H 2-reduced Pt/MoO 3 was hindered, probably by its porous structure. We suggest from these results that the low catalytic activity of H 2-reduced Pt/MoO 3 for heptane isomerization can be caused by steric effects as well as by the strong adsorption of heptane.