A very low-temperature (95 degrees C) aqueous solution route has applied to growing epitaxial ZnO films on Al2O3 (0001). A 500-nm-thick ZnO film was beforehand deposited on Al2O3 (0001) by sputtering as a buffer layer to enhance the homoepitaxial growth of ZnO in the aqueous solution. At an early stage of growth, hexagon-shaped ZnO microcrystals grow. At later stages of growth, the hexagon microcrystals coalesce, finally producing continuous epitaxial films of ZnO, which has been confirmed by high-resolution X-ray diffraction studies.