Vertically aligned carbon nanotubes/graphene oxide nanocomposite (VACNT-GO) has been prepared and applied as electrode material. First, dense packets of VACNT were prepared in microwave chemical vapor deposition reactor, and then functionalized by oxygen plasma etching. We observed that oxygen plasma could exfoliate carbon nanotubes tips and provide oxygen group attachment on its surface, changing its wettability as well. This change in wettability of the VACNT is crucial for its electrochemical application, since as-grown VACNT is super-hydrophobic. After exfoliation and functionalization, the electrochemical tests were performed using potassium ferrocyanide. The cyclic voltammetry (CV) and impedance spectroscopy revealed fast electron transfer kinetics on this new material. The CV peak potential separation was 59 mV, suggesting ideal reversibility at the electrode. The Nyquist and Bode plots were well-fitted as modified Randles equivalent electrical circuits with non-charge transfer impedance. This new highly porous nanostructures have been intensively characterized by scanning electron microscopy, Brunauer-Emmett-Teller surface area, surface wettability, Raman and X-ray photoemission spectroscopy. Our results suggest this new material has a relevant potential for future applications in electrocatalysis and (bio)sensors. (C) 2013 Elsevier Ltd. All rights reserved.