The propensity to oxidation of different chemical entities is analysed through their reduction/oxidation potentials. By observing these values alone, the thermodynamic propensity for a reaction to happen can be readily estimated. In Figure the computed oxidation potentials of probable intermediates in the NOS bond formation are shown. It can be observed that the oxidation of the thiol/thiolate moiety leads to lower oxidation potentials when compared to the amino moiety, thereby making the former proner to oxidation, as it is generally known. The results follow chemical common sense that in the first stage of the oxidation, the thiol moiety is the one likely to be oxidised.