Oxidation of several silylthiophene oligomers has been studied in dichloromethane and acetonitrile by cyclic voltammetry. Detailed mechanistic studies show that the oxidative coupling of silyloligothiophenes involves the carbon-carbon bond formation between two cation-radicals, as previously observed for other non-silylated oligothiophenes. The lifetimes of the cation-radicals are found to be dependent on the solvent, indicating a nucleophilic assistance to the C-Si cleavage. This behavior is in agreement with a reversible coupling step leading to the formation of a dimeric cation followed by the irreversible cleavage of the C-Si bond. Evidence for the existence of an equilibrium between the monomeric cation-radical and an associated form (pi-dimerization) has been obtained from the variation of the redox potential with the temperature and concentration for the most stable cation-radical.