An experimental and theoretical study on the relationships between oxidative reactivity, thermochemical viability, and structural requirement of the activity sites in oxidative desulfurization (ODS) process has been performed. A series of aromatic sulfur compounds and peroxo-metallate complexes of WOx-ZrO2 with different structures have been studied. The models chosen for mimicking the catalyst correspond to surface densities of similar to 7 W nm(-2). The results indicate that the ODS takes place in two consecutive stages: (i) the formation of sulfoxide and (ii) the formation of sulfone. However, a detailed analysis suggests that these stages occur in two separated steps, (a) addition and (b) elimination, involving the formation of intermediate adducts and that the elimination of sulfoxide from the site surface is the rate-determining step. The results also reveal that the thermochemical feasibility of the studied reactions depends on both: the local structure of the WOx-ZrO2 surface and on the nature of the aromatic sulfur compound. It was found that the reactions involving dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (46DMDBT) are the most favored reactions, while the reaction of thiophene (Th) is the least favored. Therefore, highly substituted dibenzothiophenes are the most readily oxidized species, which is in agreement with experimental evidence. An explanation to the different reactivity shown by sulfur compounds, during ODS processes, is provided. (C) 2011 Elsevier Inc. All rights reserved.