Synthesis of two conducting polymers containing 3-hexylthiophene and 3-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]thiophene is demonstrated. In thin-film transistors, the high-molecular-weight polymer shows an average mobility of 4.2 × 10 −4 cm 2 V −1 s −1 . Most importantly, the polymers have high conductivity upon doping with iodine and also have high stability in the doped state with high conductivities measured even after 1 month. Furthermore, the doping causes transparency to thin films of the polymer and the films are resistant to common organic solvents. All these properties indicate a great potential for the iodine-doped polymer to be used as an alternative to commercially available poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate). © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1079–1086.