Indium tin oxide (ITO) thin films were deposited on polyethylene terephthalate (PET) substrates at room temperature by RF magnetron sputtering with a new technique, called gas-timing. The influence of RF power on properties of ITO thin films was investigated. From the x-ray diffraction measurement of the ITO thin films grown by this technique, cubic nano-crystalline structure with predominant (222) and (400) orientation was observed. It was found that the increasing of RF power yielded to decrease in the sheet resistance of ITO thin films. The sheet resistance of ITO thin films deposited by RF power of 40 watts had the lowest value of 8 Ω/Square. By the gas-timing technique, the ITO thin films on PET substrates were achieved with high transmittance in visible region of 90%. Therefore, the gas-timing RF magnetron sputtering is a promising technique to achieve the ITO thin film on PET substrate with low resistivity and high transmittance in visible region without substrate heating and post-deposition annealing. [DOI: 10.1380/ejssnt.2005.272]