Radiation impact on water and other molecules dissolved in water represent an important applicative physics domain that could help students to better understand the interactions of ionizing radiation with matter. The study presented in this paper was carried out by young colleague that took part to specific experiments during Erasmus program and has continued the investigation by mathematical modeling. The main purpose was to model one of pollutants from waste waters, the gallic acid, and its possible radiolytic products using suitable molecular modeling software.