Exfoliated polyaniline (PANT)/clay nanocomposites were prepared by in-situ polymerization of aniline onto pre-exfoliated water-soluble poly(styrenesulfonic acid-co-aminostyrene) (P(SSA-co-AMS))/ clay nanocomposite or by simple blending of poly(styrenesulfonic acid-g-aniline) (PSSA-g-PANT) with clay. When an aqueous mixture of P(SSA-co-AMS) and clay was treated with 1 M HCl (aq), clay layers are exfoliated into the polymer matrix due to the electrostatic interaction between the positive charge of nitrogen (NH3+) in P(SSA-co-AMS) and the negatively charged surface of clay layers. The electrical conductivity of the nanocomposite is slightly lower than that of pure PSSA-g-PANT, but the thermal stability and coatability of the nanocomposite become better compared with PSSA-g-PANT.