ZnSn(OH) 6 regular octahedrons were successfully synthesized through a simple hydrothermal method using an aqueous solution containing ZnO flower-like structures, SnCl 4 โข5H 2 O, and NaOH. Phase structure, morphology and microstructure of the samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Parameters in preparation process such as the ratios of Sn 4+ /OH -, the molar ratio of Zn/Sn and reaction time were discussed. Results show that the obtained samples are comprised of ZnSn(OH) 6 regular octahedrons with about 2 ฮผm in side length and ZnSn(OH) 6 urchins-like structures. ZnSn(OH) 6 urchins-like structures preferentially grow on the edges and corners of regular octahedrons. Morphology of the products is susceptible to the ratios of Sn 4+ /OH -. A relatively low concentration of OH -is favored to obtain ZnSn(OH) 6 regular octahedrons with urchins-like structures on the surface, while a high concentration of OH -results in a handful of regular octahedrons without urchins-like structures on the surface. When the molar ratio of Zn/Sn changes to 1:2 or 2:1, the edges and corners of regular octahedrons become coarse and urchins-like structures disappear from the surface. More urchins-like structures form on the surface of regular octahedrons and the edges and corners of regular octahedrons become coarsened with the increase of reaction time. Moreover, the possible mechanism for ZnSn(OH) 6 regular octahedrons is discussed.