Nano-writing of intrinsically conducting polymer was achieved via a novel electrochemical nanolithographic technique using tapping mode electrochemical atomic force microscopy. Conducting polymer nanolines as small as 58 nm width were obtained and the line width is controlled as a function of the writing speed and writing potential. Higher writing potential and slower writing speed produce wider conducting polymer nanolines due to enhanced propagation. No specific restriction in the choice of substrates and the ease of controlling feature size is expected to facilitate to fabrication of all plastic nano-electronic devices.