The electrochemical oxidation of several silyl enolethers (SE) formed from a variety of differently substituted alpha- or beta-tetralones by side chains is described. The behaviour of the cation radicals of the SE has been found to be strongly dependent on the substituted lateral chain, especially when the substituent contains a cyclizable group like a double bond. The difference between the oxidation potentials has been attributed to the occurrence of a first order chemical reaction between the cation radical and the substituent, which is probably a cyclization reaction. The relative rates of this reaction have been discussed in relation to the substituent.