We demonstrate the microstructure and room-temperature H-2 sensing properties of undoped, Pt-doped, and Pd-doped SnO2 nanowires (SNWs). SNWs with a tetragonal structure were synthesized by thermal evaporation of tin grains at 900 degrees C. Gas sensors based on undoped, Pt-doped, and Pd-doped SNWs showed a reversible response to H-2 at room temperature. The response was improved in the order undoped < Pt-doped < Pd-doped SNWs under the same conditions.