Effects of H₂ reduction on the catalytic properties of MoO₃ with Pt, Pd, Rh, Ir, or Ru for the conversions of heptane and propan-2-ol were studied. The catalytic activity of MoO₃ with noble metal for the isomerization of heptane was strongly dependent on the period of H₂ reduction at 623 K. This behavior was almost the same as that of MoO₃ without noble metal. Among the catalysts tested, Pt/MoO₃ was the most active for this reaction. The catalytic activities of MoO₃ for dehydration and dehydrogenation of propan-2-ol also increased in proportion with the period of H₂ reduction. In the case of MoO₃ with noble metal, a higher dehydration activity was obtained by a longer period of H₂ reduction, while the dehydrogenation activity was almost independent of the reduction period. Pt/MoO₃ exhibited a high dehydration activity compared with the other catalysts, indicating the most acidic property of Pt/MoO₃. We conclude from these results that the high isomerization activity of Pt/MoO₃ can be attributed to its high acidity as well as to the hydrogenative and dehydrogenative properties of Pt metal.