The conical nanotube structure of polyaniline (PANI) was facilely synthesized on indium tin oxide (ITO) conducting polyethylene terephthalate (PET) substrates via electrochemical polymerization method. The tubular morphology of PANI was confirmed by SEM and TEM images. It was observed that one side of PANI conical nanotube was a sharp closed tip, and the other was a circular open tube. In addition, the nanosheets, nanofibers and nanorods of PANI were observed by SEM with polymerization potentials varying from 2.0V to 2.6V. The resulting materials were also characterized by four-probe instrument, FTIR, cyclic voltammetry, and photoelectric measurement. Then the results showed that the optimal efficiency of dye sensitized solar cell (DSSC) with flexible PANI/ITO-PET counter electrode at 2.4V reached to 0.86%, owing to the unique conical nanotube structure, excellent photoelectric property and high electrochemical activity of this PANI electrode. Therefore, the PANI/ITO-PET electrode can be applied as promising flexible electrode materials for DSSCs. (C) 2012 Elsevier Ltd. All rights reserved.