Branched nanofibers of conducting polyaniline (PANI) buried in the crystals of camphor sulfonic acid (CSA) were prepared from an m-cresol solution of PANI and excessive CSA. After the excessive CSA was dissolved through ultrasonication in deionized water, networks of PANI nanofibers with spherical nodes, nanoparticles, leaf-vein-shaped nanofibers, and so forth were obtained according to the strength of the ultrasonic treatment. The X-ray diffraction patterns of the CSA-doped PANI showed high crystallinity. (C) 2002 Wiley Periodicals, Inc.