Polymeric nanowires of poly(3,4-ethylenedioxythiophene) (PEDOT) are electrochemically synthesized using porous anodic alumina oxide (AAO) membranes as templates. Four-point resistivity measurements on more than 100 PEDOT nanowires with different diameters (50-250 nm) reveal a statistically significant size-dependent phenomenon in which the nanowires with a smaller diameter exhibit higher conductivity. Structural characterization with Raman spectroscopy and doping level estimation with energy-dispersive X-ray spectrometry and X-ray photoelectron spectroscopy indicate that the observed conductivity enhancement can be attributed to improved carrier mobility in PEDOT nanowires having an elongated conjugation structure because of the effect of the AAO template. From the estimated doping levels (similar to 5%) and conductivity data (similar to 100 S/cm), it is found that the carrier mobility reach 2.0 cm(2)/V s for the nanowire with the smallest diameter, as compared with 4.0 x 10(-4) cm(2)/V s for a bulk PEDOT film. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1762-1768, 2011