A novel method of electrolytic Indium oxide coating has been investigated in In-2(SO4)(3)(.)9H(2)O aqueous solution. Through cathodic polarization tests, three major reactions were verified: (1) O-2+4H(+)+4e(-) -> 2H(2)O (similar to 0.6 to -0.25 V), (2) 2H(+)+2e(-) -> H-2 (-0.25 to -0.6V), (3) 2H(2)O+2e(-) -> H-2+2OH(-) (-0.6 to -1.5 V). The coated specimens obtained at the third stage were further annealed and characterized by Fourier transform infrared (FTIR), thermo-gravimetric/differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The TGA curve of the as-coated films was divided into four steps. The first and second were the evaporation of physical water from 2 In(OH)(3) surface between 20 and 200 degrees C, transformed into 2InOOH by the removal of 2H(2)O from the gel bulk, corresponding to 10% weight loss, between 200 and 300 degrees C, and finally condensed into In2O3 and H2O, corresponding to 5% weight loss, between 300 and 500 degrees C. From cross-sectional view, the In2O3 coated film with thickness of about 100 nm revealed excellent adhesion with substrate. Particles exhibit a uniform distribution in terms of the particle shape, size and texture. (c) 2005 Elsevier B.V. All rights reserved.