This paper reports charge transport mechanism of polythiophene (PT) and its nanocomposites having various weight of zirconium dioxide (ZrO2). Fourier transform infrared (FT-IR) spectral studies showed that the Zr ions mostly affected the C-S bond of the polythiophene. X-ray diffraction (XRD) patterns indicated that ZrO2 powder was a mixture of monoclinic (64.62%) and tetragonal (35.38%) phase. XRD measurements revealed that crystallinity of PT decreased with increasing doping level. Significant morphological differences were observed in scanning electron microscopy (SEM) images of PT depending on the doping process. Thermal analysis carried out by differential scanning calorimetry (DSC) indicated that the doping processes increased glass transition temperature of PT. The alternating current (ac) conductivity mechanism analysis by universal power law indicated that charge transport mechanism of both PT and PT/ZrO2 nanocomposites was consistent with correlated barrier hopping (CBH) model. The doping process and frequency affected the hopping distance between the sites. (C) 2015 Elsevier Ltd. All rights reserved.