The in situ electrical conductivity (resistance) of electrochemically prepared polyindole (PIn) in ionic liquids was found to be strongly dependent on the nature of the solvents, size of ionic liquid counter ions and preparation technique. Accordingly, the conductivity can be enhanced by about one order of magnitude when using a 1-butyl-3-methylimidazolium tetrafluoroborate [BMIm] [BF4-] or 1-butyl-3-methylimidazolium hexafluorophosphate [BMIm] [PF6−] in comparison to acetonitrile (ACN). Moreover, the growth of polyindole in ionic liquid on gold electrode surface is faster than growth of polymer in acetonitrile. Additionally, a significant enhancement of the conductivity by using ionic liquids during the polymerization could be achieved. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40094.