This paper shows the possibility to apply the Langmuir-Blodgett (LB) techniques for the preparation of ultrathin films of various ionomeric polymers, namely Nafion((R)) (perfluorinated cation-exchanger), Tosflex((R)) (perfluorinated anion-exchanger) and Eastman AQ55((R)) (polyestersulfonated cation-exchanger). The pressure-area isotherms and the condensation degree of the interfacial films depend on the chemical structure of the ionomer and on the nature of the electrolyte dissolved in the subphase. The addition of a strong electrolyte to the subphase is, in fact, a compulsory requirement in order to allow the formation of a stable ionomer layer at the air-water interface. The interfacial film can be transferred by LB deposition technique onto substrates such as glassy carbon, gold or indium-tin oxide electrodes. Quartz crystal microbalance data indicate the uniformity of such LB-coatings and ion-exchange voltammetric measurements confirm their ion-exchange preconcentration capabilities. Films based on perfluorinated ionomers such as Nafion((R)) and Tosflex((R)) are characterized by higher condensation degrees and are closer to reach a monolayer packing than films based on the polyestersulfonated Eastman AQ55((R)). (C) 2004 Elsevier Ltd. All rights reserved.