ZnSe semiconductor aggregations were prepared via gamma-ray irradiation method. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images of the products clearly show that ZnSe possesses an aggregation structure, and these aggregations were found to form through the aggregation of ZnSe nanorods. The length and the diameter of the ZnSe nanorods are about 500-1000 and 30-60nm, respectively. Electron diffraction patterns of an individual ZnSe nanorod and X-ray diffraction (XRD) analysis were used to examine the crystal structure of the products. The obtained product is pure-phase hexagonal system ZnSe. The composition of the products was analyzed by X-ray photoelectron spectroscopy (XPS). Effect of the pH value on product morphology was investigated.