We report the growth and properties of highly c-axis oriented ZnO films, by radio-frequency magnetron sputtering, on the growth side of freestanding chemical vapor deposited diamond film-substrate. Low-temperature ZnO buffer layer is required for the formation of continuous ZnO films. The morphology, structure, and optical properties of the ZnO films deposited are strongly dependent on the thickness of the buffer layer. The optimized thickness of ZnO buffer layer is about 10 nm to realize high-quality ZnO films having small compressive stress and high intensity ultraviolet emission. The ZnO/diamond (growth side) system is available for the applications in numerous fields, especially for high performance surface acoustic wave devices. (C) 2010 Elsevier B.V. All rights reserved.