The potential-assisted copper-catalyzed alkyne-azide cycloaddition was investigated to modify a gold electrode surface. Firstly, a tetrathiol-hexynyl derivative was used to introduce alkyne functions on the surface. This anchor proved its robustness in conditions used for the "click" reaction and in wet storage. Then, the potential-assisted "click" reaction was studied with an azido ferrocene derivative. The experimental conditions were optimized according to the electrochemical response of the sensor by cyclic voltammetry and the "click" reaction yield was established. After functionalization, the presence of the 1,2,3-triazole group was confirmed by XPS. A fluorescent azido oligonucleotide was grafted onto the gold surface allowing visualization of the reaction by fluorescence microscopy. (C) 2013 Elsevier Ltd. All rights reserved.