The adsorption dynamics of Imidazol (Imid) and Imidazolium (ImidH(+)) on copper was investigated by Surface-Enhanced Raman Scattering (SERS) as a function of the applied potential and pH. Although both species adsorb on metal surfaces the neutral molecule changes the orientation from tilted to perpendicular as the potential is made more negative. On the other hand, the cation remains parallel over the whole studied potential window. Imid is the major species on copper electrode, although ImidH(+) can be identified even in alkaline solutions. Cyclic voltammetry and chronoamperometry measurements show good correlation with SERS data in terms of CuCl (CuCl2 as well) and Cu2O formation. Initially, a chemisorption mechanism is proposed at cathodic potentials, which changes to physisorption near the copper corrosion potential and finally a soluble complex is formed at more positive potentials. Such findings indicate that Imid is a good cathodic inhibitor, but its inhibition efficiency is very low at anodic potentials. (c) 2018 The Electrochemical Society.