The hydroperoxide raical exhibits the highest kinetic barrier (9.4 kcal/mol) and leads to thermodynamically least favourable intermediate (-3.5 kcal/mol). The hydroxyl radical has a slightly lower activation barrier (6.1 kcal/mol) but leads to the formation of a thermodynamically much more favoured intermediate (-24.9 kcal/mol). Finally, we have considered the reaction with the hydrogen atom, which leads to the lowest ac-tivation barrier (0.4 kcal/mol) and an exergonic formation of products (-19.7 kcal/mol). Overall, the formation of the thyil radical with the studied radical species show low kinetic barriers and lead to thermodynamically favoured values. The newly formed thyil radical would thereafter recombine with the hydroperoxide radical leading to the thio-(hydro)peroxy acid species through a barrierless process (see Figure ).