Electrochemical impedance spectroscopy was used to study the adsorption of several surface active substances at the surface of non-stoichiometric copper(I) sulfide. Simultaneously the influence of the treatment of the copper sulfide by the solution of those surface active substances on the leaching rate of the sulfide in oxygenated sulfuric acid solution was investigated and correlated with the type of adsorptive bond formed between the sulfide surface and adsorbed molecules. Both chemisorption and surface precipitation may lead to the formation of a strongly bound product that prevents the dissolution of a mineral. Contrary, physical adsorption is too week to protect the surface from the attack of aggressive medium.