This work include two parts, the first part preparation of 3-[(4-Phenyl azo-phenylimino)-methyl]-phenol. In the second part Photocatalytic degradation of prepared azo dye has been studied using zinc oxide ,the suspended solution include different concentration of prepared azo dye with fixed value of 0.13gm/100cm3 zinc oxide was irradiated by mercury lamp 160 Watts inside a Pyrex photoreaction cell of 100 cm3 with 10 cm3/min of flow rate air babble and at room temperature 298 K. Several experiments are carried out in various conditions to create the best Photocatalytic degradation of prepared azo dye, the effect of concentration of prepared azo dye, the effect of mass loaded of zinc oxide, and the effect of light intensity. UV-Vis spectrophotometer has been used to investigate the products.