Nanofibers of poly(amide 6) (PA6) with different amounts of poly(aniline) (PAni) doped with p-toluene sulfonic acid (TSA) were obtained by electrospinning. The nanofibers were characterized by scanning and transmission electron microscopy (SEM and TEM, respectively), wide angle x-rays diffraction (WAXD), differential scanning calorimetry (DSC), thermo gravimetry (TGA) and dynamic mechanical analysis (DMTA). It was observed that as the amount of PAni increased, nanofibers with increasing diameters, lower crystallinities, higher decomposition temperatures, lower amounts of gamma phase and lower elastic modules and elongations at break were obtained. After immersion of the nanofibers in solutions of different pHs, it was also observed that the change in color from green (emeraldine salt) to blue (emeraldine base) was instantaneous and reversible, due to their higher surface area, different from cast films which took more than 5 min to change color. (C) 2012 Elsevier B.V. All rights reserved.