In this work ZnO/Al2O3 multilayer is deposited on PET(polyethylene terephthalate) substrate by RF sputtering in argon atmosphere and the effect of Al2O3 layer on optical, electrical and structural properties of ZnO is investigated. It is observed that the presence of Al2O3 layer between ZnO and PET reduce the transmission of light from ZnO/Al2O3/PET structure 11% but if a thin layer of SiO2 similar to 100 nm is applied between Al2O3 and PET it can be compensated. The XRD results show that the ZnO film had hexagonal wurtzite structure with (002) preferred orientation and the application of Al2O3 and SiO2 layers do not have any effect on its structure. The effect of Al2O3 and SiO2 layers on optical band gap of ZnO has been investigated, also the surface morphology of ZnO film is studied by scanning electron microscopy. (C) 2012 Elsevier Ltd. All rights reserved.