A self-assembled monolayer of 1-dodecanethiol (DT) was formed on a copper surface pretreated using different methods. The corrosion protection abilities of the monolayer were evaluated in an air-saturated 0.51 M NaCl solution using various techniques including electrochemical impedance spectroscopy, polarization, coulometry, weight loss, and x-ray photoelectron spectroscopy It was found that the corrosion resistance of the monolayer was improved markedly by using a nitric acid etching method. A minimum concentration of 10(-4) M DT was needed to form a protective monolayer. The DT-monolayer retarded the reduction of dissolved oxygen and inhibited the growth of copper oxide in the NaCl solution. In comparison with other inhibitors, such as benzotriazole (BTA) and mercapto-benzothiazole (MET), the DT-monolayer showed much better corrosion resistance in aqueous solution.