A variety of oxidation products can be formed departing from the thiol/thiolate moiety. The thyil radical, sulfenic and sulfininc acids lead to the lowest values and are therefore thermodynamically the most favourable oxidation products. However, it should be remarked that the formation of the sulfinic acid is known to be a thermodynamic trap. Due to its high thermodynamic stability the reaction would be at a dead end. In order to reduce this product, one would require some sort of catalysis, which in nature can be achieved by cysteine sulfinic acid reductases. This implies that sulfinic acid cannot play a role as an intermediate and that a species at a lower oxidation state is required. This would include species such as the thiyl radical, the sulfenic acid or the thio-(hydro)peroxy acid, which would allow the reaction to proceed, ultimately leading to the formation of the NOS bond. Further oxidation reactions of the already oxidised thiol/thiolate and amine moieties are shown in Figure . It can be seen that the thio-(hydro)peroxy acid is the most unstable species (potentials below -1.6 V). Once formed it can be reduced to the thyil radical or sulfenic acid, while potentially oxidising nearby chemical entities. We have then considered potential oxidant agents (Figure ), in conjunction with Equations ( ) and ( ), in order to obtain an estimate for the full redox process of NOS formation. It is interesting to note that the NOS formation from the amine and thiol moieties is possible with hydrogen peroxide (H 2 O 2 ), as it was reported in the experimental assays. Moreover, the potential for hydrogen peroxide reduction closely matches the potential for NOS formation, in accordance with the reported reversibility of the bond. The hydroxyl radical (•OH) displays the highest reduction potential (2.25 V) among the considered oxidants and is able to oxidize most of the chemical species under study. This value should be considered with care as this species will likely further react with water. Ground state molecular oxygen on the other hand shows the lowest reduction potential value (0.81 V). Hence, the oxidation with this species leading to the formation of a NOS bond would not be a spontaneous process.