In this project the UV/H2O2, UV/H2O2/Fe (III) and UV/H2O2/V (IV) processes have a grate importance because of their high rates in eliminating the pollutants and can be used in purification of sewages of chemical industries. In this research, photo catalytic destruction of some environmental pollutants such as methyl orange, methyl green and methyl blue as organic samples in sewages of chemical industries in presence of photo catalysts was investigated. The effect of different parameters such as the period of photo radiation, amount of photo catalyst, pH and temperature were investigated. Results showed that these chromogenic organic materials are decomposable in presence of hydrogen peroxide and ultraviolet radiation (UV) from mercury lamp (400 W) and also photo destruction process. Elimination of methyl orange, methyl green and methyl blue in absence of hydrogen peroxide and in effect of direct photo destruction is low and in absence of ultraviolet radiation is very low. The effect of environment pH was also investigated in all reactions and in all cases the optimum amount of pH was 7. In all reactions, it was observed that temperature has no significant effect on these reactions and destruction reaction is carried out well in room temperature. The kinetic investigations showed that the kinetics of these reactions follows the modified model of Langmiur-Hinshel Wood and first order rate rule. Finally the first order rate constant of photo catalytic destruction reaction of these materials were compared using the UV/H2O2, UV/H2O2/Fe (III) and UV/H2O2/V (IV) photo catalyst. Results showed that in all cases, the rate constant of destruction reaction in presence of UV/H2O2/Fe (III) is very more than the rate constant of reaction in presence of UV/H2O2/V (IV) and UV/H2O2 so the method of photo catalytic oxidation of methyl orange, methyl green and methyl blue using the photo catalyst of UV/H2O2/Fe (III) can be applied as a practical and useful method for elimination of these pollutants from environment.