SnO2 films with different thicknesses (250, 300, 330 and 350 nm) were synthesized by spray pyrolysis technique. The substrates were heated to 500°C. Characteristics and optical constant of the films have been studied. Optical absorption studies in the wavelength range 300Â900 nm in order to calculate the optical constants such as refractive index, extinction coefficient, real and imaginary parts of dielectric constant. Results illustrate that both refractive index and extinction coefficient of the films are increasing with increasing film thickness, on the other hand, the values of real and imaginary parts of the dielectric are found to be decreased with increasing film thickness. The skin depth is found to be decreases as the film thickness increased to 350nm, so the skin depth is a transmittance related.