Polyaniline has been synthesized and is doped with sodium thiosulphate. The doping of polyaniline (PANI) is done at two different time periods and DC conductivity is measured to see the effect of dopant. It has been observed that the crystallinity of PANI increases through doping which ultimately increases the conductivity. The conductivity result shows that the conduction is taking place through hopping process due to wide range of localized states present near the fermi level. Structural changes due to interaction of dopant species with PANI are studied through FTIR. (C) 2008 Published by Elsevier B.V.