The electrical conductivity and carrier relaxation in poly (3, 4-ethylenedioxythiophene) (PEDOT) nanofibers have been studied over a wide range of frequency and temperature by means of impedance spectroscopy. High resolution transmission electron micrographs confirm the formation of nanofibers with average diameter of 14 nm. The linear increase of imaginary permittivity with decreasing frequency in the log-log plot of e″ versus ω is attributed to the higher contribution of dc conductivity than that of the electrode polarization. The presence of single semicircle in the complex impedance Cole-Cole plot indicates the presence of single charge carrier relaxation mechanism. The perfect matching of the relaxation peak in Z″ and M″ vs. frequency at different temperature confirms the presence of Debye type relaxation. From the temperature dependent behavior of frequency exponent study it is confirmed that the charge transport takes place through correlated barrier hopping mechanism. Decrease of barrier height and increase of density of states with increasing dopant concentration can be corroborated with the conductivity enhancement.