The decomposition of di-tert-butyl peroxide (TBP) in hexamethyldisiloxane (SiH), in the presence and the absence of pentamethylvinyldisiloxane (Vi), was studied with different relative ratios of reactants. The identification of the numerous products generated during these decompositions was performed, allowing to suggest free radical and carbene reactions to account for their formation. The mechanisms advanced in the literature, to explain the cross-linking of silicones, were compared to the ones proposed for the formation of the products of the above reactions in order to confirm or to exclude the involvement of such chemical reactions in the cross-linking. This allowed the selection of the mechanism proposed by Dunham et al. and the rejection of the one of Bork and Roush. From these analyses, an explanation of the classification of this peroxide in the family of "vinyl specific peroxides" can be given.