The generation of organoperoxy radical by irradiating aqueous solutions of organochlorides depends on the concentration of organochloride, where low concentration of organochloride results in low yield of peroxyl radical. The need of high concentration of organochloride limits the application in cancer therapy as most small molecule organochlorides show liver toxicity at elevated concentrations. To study if the oxidation is feasible at low concentration of organochloride, we proposed a reaction network where the effect of molecular oxygen is included. We hypothesized that oxygen competes with the organochloride to react with aqueous electrons, thereby causing a low yield of peroxyl radical at low organochloride concentrations. However, oxygen is necessary in the peroxyl radical formation pathway, which complicates straightforward prediction of reaction outcome. We developed a mathematic model to simulate the yield of peroxyl radical depending on organochloride and oxygen concentrations. The simulated results indicate that at low organochloride concentration, decreasing oxygen concentration