Self-assembled monolayer of allylthiourea (AT) was first formed on copper surface. 1-Dodecanethiol (DT) was then self-assembled on ihe surface for subsequent modification. Finally, AC voltage was loaded on copper covered with the mixed film for further improvement. After these processes, an effective inhibition film was obtained as indicated by the high charge-transfer resistance shown in electrochemical impedance spectroscopy and low corrosion current density in polarization curves. The maximum coverage and inhibition efficiency for copper corrosion was 98.6 % and 98.5%, respectively. The mixed film was stable in a wide range of potential before and after AC voltage treatment

Key words: THIOUREA P, MERCAPTAN, STABILITY, IMPEDANCE, CORROSION