We investigated the applicability of individual multiwalled carbon nanotubes (MWNTs) as nanoelectrodes for high sensitivity electrochemical measurement and device miniaturization. An individual MWNT is split into a pair of nanoelectrodes with a gap between them by reactive ion etching in oxygen. Electrical contacts were provided by nanolithography to the two MWNT sections, which acted as the working and counter electrodes. Using a quasi-Ag/AgCl reference electrode, the nanoelectrodes were subject to cyclic voltammetry inside a 2 mu L droplet of dopamine solution. An excellent electrocatalytic behavior was found: The observed detection limit was as low as 10 pM dopamine. Thus, the proposed MWNT electrode has a significant potential for use in highly integrated, miniaturized devices for electrochemical sensing.