The effects of O-2 plasma pretreatment on the properties of Ga-doped ZnO films on PET substrate were studied. Ga-doped ZnO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion of PET substrate, O-2 plasma pretreatment process was used prior to GZO sputtering. With increasing O-2 plasma treatment time, the contact angle decreases and the RMS surface roughness increases significantly. The transmittance of GZO films on PET substrate in a wavelength of 550 nm was 70-84%. With appropriate O-2 plasma treatment, the resistivity of GZO films on PET substrate was 3.4x10(-3) Omega cm. (C) 2010 Elsevier B.V. All rights reserved.