The spontaneous adsorption of thiols on metal substrates such as gold has allowed the preparation of well-ordered structures at the molecular level.Self-assembled monolayers (SAMs) can protect metals from oxidation,and thiol molecules can greatly enhance the rate of copper electrodeposition in the presence of chloride ions.Modification and functionalization of metal electrodes with self-assembled thiol adlayers opens manifold possibilities for electrochemical investigations.Thiol molecules with various functional groups have different adsorptive capability.The behaviors of different thoil SAMs on Au(111) in sulfuric acid solution was studied using cyclic voltammetry (CV).The reductive desorption process of thiols occurring at more negative potentials is characterized by a single desorption peak in the voltammetic responses using NaOH as an electrolyte.Results show that the composition of the immersion solution for SAM of the thiol molecules with a sulfonic acid is critical,whereas the composition of the immersion solution is not critical for SAM of the thiol molecules with other end groups.