Electrode deposits of a polythiophene with particularly interesting characteristics, i.e., poly[4,4'-bis(butylsulphanyl)-2,2-bithiophene], have been generated in the presence of different supporting electrolytes. The formation of the coatings has been studied by coupling conventional electrochemical techniques with quartz crystal microbalance measurements. The results of simultaneous voltammetric or chronoamperometric and microgravimetric experiments allow us to show the influence exerted by the nature of the supporting electrolyte on the polymerisation and concomitant charging-discharging processes of the conducting polymer. (C) 2003 Elsevier B.V. All rights reserved.