To improve the performance of sensor, a conductive polymer is considered to use as active sensor material. Polyaniline is active polymer which is possible to be used in has wide application by using dopant variation. This work discribes a study of monomer aniline synthesis mechanism to be nanofiber polyaniline by using interfacial polymerization with variable dopant concentration. The propossed dopant in this work hydrochloric acid (HCl). This paper present the use LCR meter to explore electrical properties, FTIR and UV-visible characterizations to explore more properties nanofiber polyaniline produced by variation of molar dopant. The results of this study indicate that the increase in dopants molarity give effect to the increment of conductivity. Based on Fourier Transform Infrared spectroscopy, there is peak shifting of vibration characteristic of each dopant concentration. Hasil spektroskopi UV-Visible spectroscopy shows that higher molar concentration of dopant has make absorbance value of nano fiber polyaniline becomes smaller.