The electrochemical replacement method to form epitaxial adlayers of fullerene on Au(lll) surfaces was proposed and demonstrated by in situ electrochemical STM. The new "wet process" method consists of the transfer of Lanmuir films of fullerene onto iodine-modified Au(lll) surfaces at an air-water interface followed by the electrochemical removal and replacement of iodine adlayers with fullerene adlayers in solution. The fullerene adlayers prepared by this method showed excellent quality and uniformity, and they were essentially the same as epitaxial adlayers prepared by sublimation.