Endocrine disruptors (EDs) are a group of organic pollutants, which have negative effect on the hormonal systems of organism. For example, they can be toxic for the hormonal systems in fish, resulting in decrease in fertility. Conventional wastewater treatment is not successful in removal of EDs, therefore heterogenous photocatalysis is studied as an effective removal tool. The aim of this study was to optimize a method of photocatalytic removal of 4-tert-octylphenol, an endocrine disruptor present in wastewater. TiO2 P25 was used as a photocatalyst, UV light was used for irradiation. Various amounts of photocatalyst in the reaction mixture as well as various irradiation intensities were applied. P25 was applied to 25 mL of 10-4 M solution of 4-OP as a free powder. The reaction mixture was irradiated using UV light (365 nm) for 5 hours. An array of concentrations of P25 (1, 2, 4, 8 and 16 mg, irradiation intensity 1.1 mW cm-2) and of irradiation intensities (1.1, 3.6, 6.7 and 8.5 mW cm-2, mass of P25 2 mg) was used. Aliquotes were taken from the reaction at time intervals and were analyzed using RP-HPLC-DAD detection. From the data obtained, it was determined that the reaction rate increases with the increasing amount of photocatalyst added in a dependence following the Langmuir-Hinshelwood kinetics. It is proposed that the reaction rate would reach a plateau when more than 16 mg of P25 is added. However, the increase of the P25 amount complicates the separation of the photocatalyst from the reaction mixture when the reaction is over–centrifugation is more difficult. Overall, 4 mg of P25 was sufficient for complete removal of 4-OP after 5 hours, 8 mg was sufficient for complete removal of 4-OP after 3 hours. When an irradiation intensity of 3.6 mW cm was used, the complete removal of 4-OP was achieved at 5 hours. When the intensity was increased to 8.5 mW, 1.5 hours was enough to completely degrade 4-OP. Overall, an ideal experiment for total degradation of 4-OP was proposed–2 mg P25 and 6.7 mW cm-2. Furthermore, experimental conditions for following the kinetics of the reaction were optimized at 2 mg P25 and 1.1 mW cm-2. In this study, a photocatalytic degradation of 4-OP was studied. The dependence of reaction rate on both the mass of photocatalyst in the reaction mixture and the irradiation intensity was examined. It was determined that the dependencies were Langmuir-Hinshelwood kinetics and linear in the studied range, respectively. These results will be further applied on optimizing experiments using immobilized photocatalysts, which is more suitable for industrial use.