The kinetics of oxidation of p-X-benzyl phenyl- and p-Y-phenyl benzyl sulfides by V(V) oxo-monoperoxo complex [PicVO(O-2)] (Pic = picolinic acid anion) in acetonitrile at 20 degrees C is reported. The oxidation reaction leads to the formation of the corresponding sulfoxides and to oxygen produced from the oxidant decomposition started by the substrate. The change of the obtained sulfoxide-emitted oxygen ratio in p-Y-phenyl benzyl sulfides seems to be due to the substituent type used in the substrate, whereas when the substituent is isolated from the reaction centre, as in p-X-benzyl phenyl sulfides, the sulfoxide and oxygen emitted are not influenced by the substituent. Moreover the products obtained from the oxidation of some p-X-toluenthiols (the corresponding aldehydes) suggest the hypothesis of a possible pathway for the oxygen transfer step for these reactions. The process seems to require coordination of the organic sulfide to the metal, followed by oxidation within the coordination sphere. (C) 2009 Elsevier B.V. All rights reserved.