This work describes the attempts to develop a new type of modified electrode with high selectivity towards uranyl ions, UO22+. This goal has been addressed by binding derivatives of calix[6]arene, which is it macrocyclic molecule composed of six phenol units, known as "super uranophile", to the electrode surface. Selective extraction of UO22+ onto the electrode surface, followed by a voltammetric measurement provides a quantitative uranyl analysis. Our initial approach to binding calix[6]arene molecules onto electrodes has involved an ionic derivative, 4-sulfonic-calix[6]arene. which was electrostatically attached to a positively-charged self-assembled monolayer of cysteamine (2-aminoethanethiol) on a gold electrode. The attachment of the 4-sulfonic-calix[6]arene to the cysteamine monolayer was verified by XPS. IR spectroscopy and capacitance measurements. Voltammetric experiments showed that uranyl ions can be preconcentrated and measured by these modified electrodes. (c) 2007 Elsevier B.V. All rights reserved.