Effects of Pt nanoparticle incorporation into a MoO3 thin film, which was prepared via cosputtering of a Pt and MoO3 target, were investigated for a cathode electrode of the rechargeable Li batteries. The incorporation of the Pt with size of ca. 1.5 nm formed a heterogeneous film morphology with nanophases of Pt and MoO3 domains, leading to a better cyclic performance than the electrode of MoO3 without Pt. These enhancements with Pt in the MoO3 electrode could be ascribed to a combined effect of substantial decrease in the sheet resistance and amelioration of the mechanical stability of the film itself.