Abstract Investigations on the surface chemistry of the self-assembly process (chemisorption) of thiols on copper are reported. The chemisorption was investigated on copper sheets and on copper powder. Copper exposed to air is covered qith a thin oxide layer. On contact with thiols the oxidic copper species are transformed to copper thiolates by a redox raction. Cu 2+ is reduced to Cu + and thiol (HSR) is oxidized to disulphide (RS-SR). Excess thiol forms copper thiolate complexes which build up self-assembled multilayers with layer thicknesses of 20–90 nm. The self-assembled thiolate layers cause a strong hydrophobization of the copper surface.