Electrochemical fluorination of various (arylthio)methyl carboxylates was carried out in aprotic organic solvents containing poly(HF) salts to provide the corresponding O-fluoromethylcarboxylates in good to moderate yield. Electrochemical fluorination of a cyclic analogue, a γ-phenylthio-γ-butyrolactone derivative was also achieved under ultrasonication to give the corresponding 4-fluorinated product