The optical and electrical characteristics of SnO 2 films with 0.02 at.% Pt nanoparticles were studied after annealing at various temperatures. Pt nanoparticles were synthesized by a methanol reduction method and their size was limited to 3 nm on average using PVP [poly(N-vinyl-2-pyrrolidone)] as a protecting agent. The electrical conduction of the SnO 2 films was enhanced by the introduction of Pt nanoparticles without degradation of optical transmittance. The resistivity and transmittance of the SnO 2 films with and without Pt nanoparticles after annealing at 700 °C were 2.9 × 10 -2 Ω cm and 86.45%, and 1.5 × 10 -1 Ω cm and 85.75%, respectively. The observed enhancement in electrical properties was attributed to an increase in carrier concentration due to the addition of Pt nanoparticles. The fact that almost no change in transmittance was observed is explained by the small quantities produced and small particle sizes of the Pt nanoparticles. Welldefined 30-μm-wide direct-patterned SnO 2 films containing Pt nanoparticles were formed by photochemical metal-organic deposition using a simple process including a photosensitive starting precursor, UV exposure, and removal of the un-patterned area with solvent rinsing.