By conducting multiple tests, the photo degradation of the orange G dye used in industries such as investigating of varying the weight used zinc oxide as a metal oxide. The best weight used of oxide was 0.13 g/100ml as a result of obtaining the largest catalytic decomposition of the dye. It was verified that the effect of different concentration of the dye on the decomposition process. It was found that 30 ppm was the best concentration in which the largest possible amount of catalytic decomposition of the dye took place, in addition to the effect of using different volume of ethanol in the photo degradation process on the dye used. A UV-Visible spectrophotometer was used to study photo catalytic using zinc oxide as a catalyst with radiation from a 125 W mercury lamp.