The synthesis of new regioregular polyalkylthiophenes derivatives with different substituents inserted in the terminal position of a hexamethylenic side chain is described here. The new polymers were prepared by simple and effective post-polymerization functionalization of a soluble regioregular precursor, namely poly[3-(6-bromohexyl)thiophene] that was obtained by regiospecific organometallic coupling. The new materials were characterized by NMR, FT-IR, elemental analysis and their molecular weights determined by gel permeation chromatography. High-precision UV-Vis analyses (solvatochromism and affinitychromism) were conducted in solution and in film state, and the results are discussed in relation to the different inserted functional groups. Thanks to the good sensitivity and chromic response recorded for the prepared materials to different analytes and in some solvating systems, they appear to have great potential for use as electronic sensors in chemo-recognition applications. (C) 2007 Elsevier Ltd. All rights reserved.