In the present work, anodization of zinc foil was investigated in a mixed electrolyte of ammonium sulfate and sodium hydroxide under the influence of different anodization times and concentrations of the electrolyte while the temperature and voltage were kept constant. The ZnO nanoflake arrays formed on Zn foil were characterized using a field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX) analysis, and X-ray diffraction (XRD). The size of the nanoflakes increased as the anodization time increased, while increasing the concentration of (NH(4))(2)SO(4) increased the dissolution of the nanoflakes. Upon stirring, the nanoflakes that formed were more uniform and smaller in size. The catalytic activity of ZnO nanoflakes in the photodegradation of methyl orange (MO) solution under UV irradiation was evaluated. The results indicated that the surface morphology, size, and surface area of ZnO nanoflake arrays were key factors influencing the efficiency of ZnO in the photodegradation of MO.