Direct polymerized polyaniline (PANI) nanostructures, i.e., nanospheres (NSs) and nanorods (NRs), are grown using different precursor conditions via electroless surface polymerization and examined by scanning electron microscopy images, attenuated total reflectance-fourier transform infrared spectroscopy. Due to excess available area for more redox reactions, PANI-NR electrode has shown remarkably higher specific capacitance than PANI-NS. The scan-rate effect on PANI-NR electrode is studied, and finally, diffusive resistance of PANI-NS and- NR electrodes is investigated using impedance measurement. (C) 2008 The Electrochemical Society.