A large amount of chlorofluorocarbons (CFCs) is still in use in the world, although they are known to cause depletion of the ozone layer in the stratosphere. It is desirable that CFCs are converted to compounds that are recyclable as industrial materials. In this paper, we attempted the efficient conversion of CFC-12 to tetrafluoroethylene under high pressure. Under the high-pressure condition, the constant supply of CFC-12 to the electrode is expected to enhance the dimerization of the reaction intermediates. At a Pb electrode, it is known that the C-Cl bond of CFC-12 is selectively broken in aqueous solution, TFE was produced with a current efficiency of 43.2%, whereas TFE was hardly produced at Ag and Cu electrodes that are known to break both the C-Cl bond and C-F bond of CFC-12. The current efficiency for the TFE formation was largely dependent on the potential imposed on the electrode. The current efficiency for the TFE formation was improved to 70.7% at - 1.5 V versus Ag. By trapping the reaction intermediate, the reaction mechanism under high pressure CFC-12 at a Pb electrode was presumed to proceed via dimerization of difluorocarbene.