Niobium-doped tin oxide thin films were deposited on glass substrates by the chemical spray pyrolysis method at a substrate temperature of 400 A degrees C. Effects of Nb doping on the structural, electrical and optical properties have been investigated as a function of niobium concentration (0-2 at.%) in the spray solution. X-ray diffraction patterns showed that the films are polycrystalline in nature and the preferred growth direction of the undoped film shifts to (200) for Nb-doped films. Atomic force microscopy study shows that the surface morphology of these films vary when doping concentration varies. The negative sign of Hall coefficient confirmed the n-type conductivity. Resistivity of similar to 4.3 x 10(-3) Omega cm, carrier concentration of similar to 5 x 10(19) cm(-3), mobility of similar to 25 cm(2) V-1 s(-1) and an average optical transmittance of similar to 70% in the visible region (500-800 nm) were obtained for the film doped with 0.5 at.% niobium.