In this study, a novel process for depositing tin oxide thin films by electrodeposition has been developed. Amorphous phase of the as-deposited film was obtained at the temperature of 85degreesC. Nanocrystalline SnO2 having tetragonal structure with a grain size in the range of 4 to 7 nm was obtained by heat-treatment at 400degreesC in a vacuum for 4 h. Porous, dense, and uniform morphologies for the deposits can be obtained by controlling current density during deposition. Results of infrared spectra, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses were described and correlated with the process of deposition and characteristics of the resulting SnO2 films. (C) 2002 The Electrochemical Society.