Poly(3,4-ethylenedioxythiophene)-coated carbon microfibers (PEDOT-CMFs) are materials of increasing interest for the development of ultrasensitive electrodes for neural activity recordings, or as scaffolds to promote neural tissue repair. Thus, a critical aspect is the understanding of the electrical charge transport mechanisms in the carbon microfiber/conducting polymer/electrolyte system. For this purpose, we have performed impedance measurements for PEDOT-CMF electrodes doped either with polystyrene sulfonate (PSS) or poly[(4-styrenesulfonic acid)-co-(maleic acid)] (PSS-co-MA) in phosphate-buffered saline (PBS) solution. Nyquist plots from both electrode types showed similar subdiffusion behaviours. Impedance spectra of PEDOT:PSS-co-MA-coated electrodes revealed a time-delay between the current response and the voltage imposed. This novel finding was mathematically described by a hyperbolic subdiffusion model based on a fractional Cattaneo equation. A method was used to simulate chronoamperometric curves from the impedance spectra. Comparison of the simulated curves with the results obtained from actual chronoamperometric experiments performed on the electrodes showed consistency with the anomalous diffusion processes proposed. (C) 2016 Elsevier B.V. All rights reserved.