Cyclic nanostructural polyanifines have been synthesized by means of a simple modified aqueous/organic interfacial polymerization with the aid of polyacrylic acid, and yet only nanofiber nanostructural polyanilines were obtained by conventional interfacial polymerization in the presence of polyacrylic acid. These nanostructures were characterized using TEM, X-ray diffraction and UV-vis. The cyclic polyaniline nanostructures were formed by severe secondary overgrowth through the electrostatic interaction between aniline/oligoaniline and polyacrylic acid chains. The average diameter of the obtained cyclic-structure was ca. 400 nm and its conductivity was 1.06 S/cm. (c) 2006 Elsevier Ltd. All rights reserved.