The transparent conducting CuInO2 thin films were prepared by radio frequency (RF) reactive sputtering and post growth annealing. A study of structural, optical, and electrical properties was performed on the films. The crystalline phase in the films was identified to be the delafossite structure. The optical properties, such as the wavelength dependence of the transmittance and the band gap energy, were determined. The average transmittance is 70% in the wavelength range of 400-1100 nm and the band gap is ˜3.7 eV. The temperaturedependence of electrical conductivity in the CuInO2 delafossite thin films was measured from 70 to 400K. The resistivity, carrier density, and mobility of the thin films at 300K were 1.8x101 Δcm, 1.6x1019 cm-3 and 2x10-1 cm2/Vs, respectively. Hall coefficient indicated that the CuInO2 thin films are n-type conductors. The electrical conductivity showed semiconducting type at room temperature.