In the previous work , we showed that reactive oxygen species (ROS) generated by radiolysis of water can react with dissolved organochlorides, leading to the formation of a potent oxidant species. The proposed mechanism is that an aqueous electron generated from water radiolysis reacts with an organochloride to form a chloride ion and a carboncentred radical. The radical reacts with dissolved molecular oxygen to form a peroxyl radical, which is a strong oxidant. The results show that the oxidation depends on the concentration of organochloride: higher concentration of organochloride leads to more pronounced oxidation. We hypothesize that the molar ratio of dissolved oxygen to organochloride affects the yield of the peroxyradical, since oxygen can compete with organochloride to react with aqueous electrons. In this work, we propose a reaction network which includes key reactions of the pathway of peroxylradical formation. Based on the proposed reaction network, we have developed a kinetic model using previously developed ChemFit software. By numerically solving the system of ODEs, we simulated the yield of peroxyradical at different starting concentrations of oxygen and organochloride (Scheme 1). The simulation suggested that, at a fixed concentration of organochloride, the yield of ROS increased with decreasing concentration of oxygen, with a peak at approximately 2% oxygen. The yield dropped to almost zero at 0% oxygen. The maximum yield was more pronounced at lower concentrations of organochloride. We then experimentally measured the concentrations of oxidizing product at selected concentrations of organochloride and oxygen. A thioether-based molecule, compound 1 (Figure ), was used as the scavenger to catch ROS. The experimental results agreed with the predicted trend, with the yield of oxidising product peaking at 2% oxygen. The agreement of simulated and experimental results further corroborated the proposed mechanism. Furthermore, we used 2,2'-thiodiacetic acid to cage the hydroxyl group of a camptothecin to test the viability of applying thioether-based cages in radiationsensitive prodrugs. The uncaging of camptothecin by irradiation with gamma-rays in a PBS solution of organochloride showed a high uncaging efficiency, which means that 2,2'thiodiacetic acid is a promising caging group. Scheme 1. The process of using a kinetic model to verify the mechanism of peroxyradical formation.