Zinc oxide has become an important material for various applications. Commercially available zinc oxide single crystals and as-grown zinc oxide thin films have high surface roughness which has detrimental effects on the growth of subsequent layers and device performance. A chemical mechanical polishing (CMP) process was developed for the polishing of zinc oxide polycrystalline thin films. Highly smooth surfaces with RMS roughness < 6 angstrom (as compared to the initial roughness of 26 +/- 6 angstrom) were obtained under optimized conditions with removal rates as high as 670 angstrom/min. Effects of various CMP parameters on removal rate and surface roughness were evaluated. The role of pH on the polishing characteristics was investigated in detail. (C) 2011 Elsevier B.V. All rights reserved.