The structural, optical and electrical properties of ZnO thin films (260 - 490 rim thick) deposited by direct-current sputtering technique, at a relatively low-substrate temperature (363 K), onto polyethylene terephthalate and glass substrates have been investigated. X-ray diffraction patterns confirm the proper phase formation of the material. Optical transmittance data show high transparency (80% to more than 98%) of the films in the visible portion of solar radiation. Slight variation in the transparency of the films is observed with a variation in the deposition time. Electrical characterizations show the room-temperature conductivity of the films deposited onto polyethylene terephthalate substrates for 4 and 5 h around 0.05 and 0.25 S cm(-1), respectively. On the other hand, for the films deposited on glass substrates, these values are 8.5 and 9.6 S cm(-1) for similar variation in the deposition time. Room-temperature conductivity of the ZnO films deposited on glass substrates is at least two orders of magnitude higher than that of ZnO films deposited onto polyethylene terephthalate substrates under identical conditions. Hall-measurements show the maximum carrier concentration of the films on PET and glass substrate around 2.8 x 10(16) and 3.1 x 10(20) cm(-3), respectively. This report will provide newer applications of ZnO thin films in flexible display technology. (c) 2005 Elsevier B.V. All rights reserved.