We report reproducible large-scale synthesis of polyaniline (PANI) nanofibers up to 100 g scale via micelle mediated soft template approach. A unique built-in amphiphilic azobenzenesulfonic acid based on renewable resource dopant was synthesized for large-scale production of PANI nanofibres. The amphiphilic surfactant exists as 4.3 nm micelle in water and it self-organized with aniline to form long cylindrical aggregates, which template for PANT nanofibers. The PANT nanofibers were found soluble in water and organic solvents and they were characterized by H-1-NMR, FT-IR, and viscosity techniques. The mechanism of the PANT nanofiber formation was investigated by dynamic light scattering, scanning electron microscopy, and high resolution transmission electron microscopy. The width of the nanofibers was precisely controlled from 130-200 nm with length up to similar to 5 pm. The absorption spectroscopic analysis of nanofibers; in water revealed that the large-scale samples (10, 50, and 100 g) were found to posses expanded chain conformation compared to that of 1 g scale sample. The wide angle X-ray diffraction patterns showed two new peaks at lower angles at d spacing of 25.5 and 13.6 angstrom corresponding to lamellar ordering of PANT chains followed by interdigitation of the amphiphilic dopant in the nanofibers. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3531-3541, 2009