Electrochemically pretreated polycrystalline nickel substrates modified with ethanolic solutions (10(-2) and 10(-1) M) of four semi-fluorinated thiols with R-F-R-H-SH structures have been evaluated by X-ray photoelectron spectroscopy, contact angles and cyclic voltammetry measurements. Our results show that it is possible to graft highly fluorinated alkanethiols on nickel surfaces, the quality of the self assembled monolayers, depending on the concentration of the dipping solutions, the dipping time as well as the length of the perfluorinated carbon chains and those of the hydrocarbon connector between the perfluorinated fragment and the thiol function. (c) 2005 Elsevier B.V All rights reserved.