Microstructures with hollow interiors, such as microspheres, microcrocks, microbowls, and micropumpkins, were prepared through the direct electrochemical oxidation of pyrrole in an aqueous solution of poly(styrene sulfonic acid) (PSSA). Scanning electron microscopy demonstrated that the microstructures possessed hollow interiors. The addition of polymeric doping ions made the skins of the microstructures very smooth, and several novel structures were observed. The morphology of the microstructures was simply modulated through changes in the electrochemical conditions. Raman and Fourier transform infrared characterizations indicated that the microstructures were made of conductive polypyrrole (PPy) doped by polymeric anions of poly(styrene sulfonate), and X-ray diffraction showed that the microstructures were amorphous. Thermogravimetric analysis indicated that PPy-PSSA composite films with microstructures had higher thermal stability than pure PPy, PPy-coated PSSA microspheres, and naphthalene sulfonic acid doped PPy microstructures. Furthermore, PPy-PSSA composite films with microstructures showed cation-exchange behavior during the redox process in aqueous solutions of sodium dodecyl benzenesulfonate. (C) 2004 Wiley Periodicals, Inc.