ZnO and a series of Ag/ZnO photocatalysts were prepared by a precipitation- irradiation method and their photocatalytic performance in photodegradation of methyl orange dye was evaluated. The physicochemical properties of the catalysts were characterized by various characterization techniques. The photocatalysts have a hexagonal phase and were highly agglomerated. TEM images showed a change in morphology of ZnO from rod to nearly spherical with the addition of Ag. Ag/ZnO catalysts exhibited better photocatalytic activity in the degradation of methyl orange compared to pure ZnO. Ag/ZnO contains 2% silver shows the best performance as photocatalyst.