Three imidazole-based compounds (imidazole, 2-mercaptobenzimidazole, and 2-mercapto-1-methylbenzimidazole) were studied as corrosion inhibitors of Cu, Zn, and a family of Cu-xZn brass alloys (x = 10−40 wt%) in 3 wt% NaCl solution. The composition of inhibitor layers on the surface was studied using X-ray photoelectron and infrared spectroscopies. The molecular adsorption modes on Cu and Zn were modelled using density-functional theory (DFT) calculations. Mercapto-based inhibitors act as efficient inhibitors on all materials studied due to the formation of inhibitor layer through bonding with nitrogen and sulphur atoms. In contrast, imidazole is a moderate inhibitor for Zn, while it is much less efficient for Cu.