Phthalates are esters of phthalic acid and appropriate aliphatic alcohol. These volatile liquids are commonly added to plastics to increase their softness, durability and flexibility. They have become widespread in the environment. Their presence in aquatic and terrestrial environments is a growing problem. Namely, phthalates are known endocrine disruptors. Therefore, for some time, scientists all over the world have been searching for a suitable method for their removal. The most commonly present phthalates in aquatic environment are: di(2-ethylhexyl) phthalate, butyl benzyl phthalate, dibutyl phthalate (DBP), and diisobutyl phthalate. In this research, the applicability of advanced oxidation processes in decomposition of DBP in water was tested. Photooxidative treatment was applied: water solutions of DBP were exposed to UV irradiation and hydrogen peroxide or sodium persulfate as the oxidants. The impact of the pH value and concentration of added oxidants on the rate of degradation and decomposition of DBP was examined (using full factorial design of the experiment). Appropriate concentration of oxidant was added into each water sample and the pH value was set to predefined value. Each experiment lasted one minute and sampling was done every ten seconds. The samples were later analyzed using high-performance liquid chromatograph. Afterwards, degradation kinetics of the present DBP was determined. The obtained results indicated that advanced oxidation processes are suitable for removal of DBP from aqueous medium. The type and the concentration of selected oxidant, as well as pH value of the solution, greatly affected the degradation process. The optimal degradation conditions for both added oxidants were at the highest tested oxidant concentration of 4 mM and at pH value of 7.