This study is intended to determine the photodegradation pathway of methyl red dye that is used in industrial applications under zinc oxide catalytic action. The light source was UV radiation emitted from a mercury lamp with a power rating of 125 Watts. The process of the current rate of degradation of methyl red dye was studied by measuring its absorbance over a wavelength range of 380–700 nm, and the point that had the maximum absorption (640 nm) was shown. The study used different weight catalysts to compare the effect on the photodegradation of the dye, where the best weight at which the dye was broken down was 0.06 g of zinc oxide at a particular level of concentration. It was studied to determine the level of photodegradation of the dye, and it was shown that at a concentration of 1 x 10-4 M, the catalyst was most effective at the dye degradation, and the temperature also had an important effect on the methyl red dye.