We report the application of ambient spray pyrolysis for the deposition of high- k polycrystalline Y2 O3 and amorphous Al2 O3 dielectrics and their use in low-voltage ZnO thin-film transistors. The films are studied by means of atomic force microscopy, UV-visible absorption spectroscopy, impedance spectroscopy, and field-effect measurements. ZnO transistors based on spray pyrolysed Y2 O 3 and Al2 O3 dielectrics show low leakage currents, and hysteresis-free operation with a maximum electron mobility of 34 cm2 /V s and current on/off ratio on the order of 105. This work is a significant step toward high-performance oxide electronics manufactured using simple and scalable processing methods. © 2011 American Institute of Physics.