ZnO micro-flowers composed of hexagonal nanorods were successfully fabricated by soft chemical technique from zinc acetate di-hydrate (Zn(CH3COO)(2)center dot 2H(2)O) and sodium hydroxide (NaOH) in 1 h refluxing. The crystallinity of the grown product was analyzed by X-ray diffraction technique revealing the as-prepared micro-flowers have hexagonal wurzite structure. Their morphology was investigated by using FESEM and TEM, which showed that well-dispersed micro-flowers of 2-3 mu m in diameter had been formed. Furthermore, the synthesized micro-flowers showed a better photo-catalytic activity in presence of methylene blue (MB) dye. Also, the Zn-2p1/2, Zn-2p3/2, and O-1s peaks in X-ray photoelectron spectroscopy clearly suggest that the grown nanostructures are pure ZnO. Additionally, high performance liquid chromatography (HPLC) and liquid chromatography-mass spectroscopy (LC-MS) were applied to observe the degradated compounds from the photo-catalytic degradation of methylene blue (MB) dye in presence of zinc oxide micro-flowers. (C) 2011 Elsevier B.V. All rights reserved.