The inhibitory effect of Rhodanine (RD) on copper in acidic media has been investigated by electrochemical impedance spectroscopy (EIS) and surface-enhance Raman scattering (SERS) spectroscopy. Roughened copper was used for EIS experiments to better compare with SERS results. The EIS results show two loops in the Nyquist plot, one of which is associated with protective film growth on the rough surface after 1 h. The SERS spectra showed a marked decrease in intensity after 1 h, which is attributed to formation of thick films opaque to the laser. The film thickness after 2 h was determined to be similar to 200 nm from atomic force microscopy (AFM). (C) 2014 Elsevier Ltd. All rights reserved.