This research includes the study of Photcatalytic degradation of Rohdamine b using Titanium dioxide anatas , which is achieved by the irradiation of suspended solution consists of different concentration of Rohdamine b with 0.13gm/100ml of mixed metal oxide semiconductor titanium dioxide anatas by using mercury lamp 160 Watts from external source inside a pyrex photoreaction cell of 100 ml at room temperature 298 K . In order to study the effect of metal oxide Titanium dioxide anatas in Photcatalytic degradation of Rohdamine b, several experiments were carried out in various conditions to attain the best Photcatalytic degradation of Rohdamine b. These experiments include the effect of hydrogen per oxide , the effect of temperature. The products was studied by using UV-Vis spectrophotometer.