High frequency characteristics of tin oxide (SnO2) thin films were studied. SnO2 thin films have been successfully grown on n-type Si (111) substrates by using a spray deposition technique. The capacitance-voltage (C-V) and conductance-voltage (G/ω-V) characteristics of the metal-oxide-semiconductor (Au/SnO2/n-Si) Schottky diodes were investigated in the high frequency range from 300 kHz to 5 MHz. It has been shown that the interface state density, Dit, ranges from 2.44 × 1013 cm-2 eV-1 at 300 kHz to 0.57 × 1013 cm-2 eV-1 at 5 MHz and exponentially decreases with increasing frequency. The C-V and G/ω-V characteristics confirm that the interface state density and series resistance of the diode are important parameters that strongly influence the electrical parameters exhibited by the metal-oxide-semiconductor structure. © 2008 Elsevier Ltd. All rights reserved.