The electrochemical fluorination of octanoyl chloride to produce perfluorooctanoyl fluoride in anhydrous hydrogen fluoride was investigated. The study was carried out in a microprocessor-aided modified Simons reactor system using a Cu/CuF2 reference electrode. The formation of polymeric tar at the anode surface was limited by the addition of a mercaptan compound and by constant current density operation. Continuous operation was achieved through frequent additions of a solution of hydrogen fluoride and reactant. Conversion of reactant to perfluorinated products was improved to 80 % with good selectivity. Experimental results of this investigation are presented and discussed. ca]To whom correspondence should be addressed.