Formation and characterization of thin films of indium hydroxide, In(OH)₃⋅nH₂O were carried out. The indium hydroxide sample was prepared in the gel form via the reaction of indium nitrate solution with ammonium hydroxide solution. After the precipitated gel was extracted using a centrifugal separator, the gel was dispersed in deionized water for several days to prepare a colloidal solution. Films dip-coated on glass substrates were heated at several temperatures. Thin films were characterized by means of XRD, SEM, AFM, thickness measurement, TG-DTA and conductivity measurement. Although only one weak peak of the (200) plane was observed in XRD patterns, the thin films could be regarded as almost amorphous. Surfaces of all the samples were found to be smooth with roughness R_max=7nm, and the thickness of each film was about 40nm. Depending on both the heat-treatment temperature of thin films and the relative humidity, the conductivity varied in the range of 10^-7-10^-3S/cm at room temperature. In addition, the conductivity measured along the surface of the sample was on the order of 10^-6S/cm which was comparable with the value measured in the direction perpendicular to the surface. These results suggested that the carriers of conduction were protons based on water incorporated in the crystallographic channels and grain boundaries of the thin films.