Nano - structured conducting polyaniline has been synthesized for various reaction periods using in-situ chemical polymerization method. The as prepared Polyaniline are analyzed via structural characterization and absorption spectroscope using X-ray diffraction (XRD) and UV-Visible spectroscope (UV-Vis). The XRD results confirm the partly crystalline and amorphous nature of the polyaniline prepared at the reaction period 23h. The average size of the crystallites estimated as 13 nm by Scherrer’s formula from XRD data are consistent with particle size estimated from spectroscopic data through Meulenkamp equation. The optical absorption spectrum establishes the formation of polyaniline under nano-regime with the band edge absorption of 1.03 eV
