We report here a low-temperature-annealed alumina/polyimide gate insulator with excellent electrical insulating properties for solution-processed ZnO TFTs. In this study, 150nm-thick polyimide and 20nm-thick alumina thin films were deposited by a simple spin-coating followed by a 200 degrees C-annealing process. With the deposition of the alumina interlayer, the surface of the polyimide film was successfully modified. We prepared ZnO TFTs annealed at 230 degrees C to investigate the potential of the prepared gate insulator. The field-effect mobility and the on/off current ratio of solution-processed ZnO TFTs with an alumina/polyimide gate insulator were 0.11 cm(2)/Vs and 1.8 x 10(5), respectively, whereas a ZnO TFTs with a polyimide gate insulator was inactive. The alumina interlayer introduced here might provide a compatible interface for the ZnO semiconductor. (C) 2014 Elsevier B.V. All rights reserved.