We reported here "aqueous-route" fabrication of In2O3 thin-film transistors (TFTs) using an ultrathin solution-processed ZrOx dielectric thin film. The formation and properties of In2O3 thin films under various annealing temperatures were intensively examined by thermogravimetric analysis, Fourier transform infrared spectroscopy, and atomic force microscopy. The solution-processed ZrOx thin film followed by sequential UV/ozone treatment and low-temperature thermal-annealing processes showed an amorphous structure, a low leakage-current density (similar to 1 x 10(-9) A/cm(2) at 2 MV/cm), and a high breakdown electric field (similar to 7.2 MV/cm). On the basis of its implementation as the gate insulator, the In2O3 TFTs based on ZrOx annealed at 250 degrees C exhibit an on/off current ratio larger than 10(7), a field-effect mobility of 23.6 cm(2)/V.s, a subthreshold swing of 90 mV/decade, a threshold voltage of 0.13 V, and high stability. These promising properties were obtained at a low operating voltage of 1.5 V. These results suggest that "aqueous-route" In2O3 TFTs based on a solution-processed ZrOx dielectric could potentially be used for low-cost, low-temperature-processing, high-performance, and flexible devices.