The aim of this work was to examine the optimal conditions for conducting experiments on the decomposition of a solution of benzyl butyl phthalate in water using several types of electromagnetic radiation: UV radiation, microwave radiation and ultrasonic radiation. The range of decomposition of the selected phthalate by the impact of individual electromagnetic radiation was determined by high performance liquid chromatography, HPLC. Benzyl butyl phthalate (BBP) is a synthetically produced phthalate ester. In the process of producing a plastic product containing BBP, it is applied as an external plasticizer and tends to migrate from that surface, becoming an environmental pollutant. This leads to the long-term presence of BBP in all parts of the environment (water, soil, air, sediment, silt, etc.), so it is especially important to recognize and know its effects on human health and the ecosystem. According to the increase in the efficiency of BBP decomposition, microwave radiation is proved to be the best solution, followed by ultrasonic radiation and finally UV radiation. The best results of BBP degradation were achieved by the microwave radiation. With Na2S2O8 oxidant in conditions of acidic pH values (pH=4) and maximum oxidant concentrations, while with H2O2 oxidant, the minimum oxidant concentration was sufficient for a significant result. From an economic point of view and from an environmental point of view, it is more acceptable to apply the decomposition of BBP with the H2O2 as an oxidant.