Nanocomposites of conducting polyaniline (PAN) with inorganic Na+-montmorillonite (MMT) clay were synthesized by the emulsion polymerization method. The dodecylbenzenesulfonic acid (DBSA) was used for both dopant and emulsifier. Analyses of X-ray diffraction patterns demonstrated that conducting PAN-DBSA was intercalated between inorganic clay layers at the nanoscale level (< 10 Angstrom). We observed that the clay induced more disordered state in PAN-DBSA/clay nanocomposites. From the temperature-dependent dc conductivity [sigma(dc)(T)] experiments, we investigated charge transport mechanism of the PAN-DBSA and PAN-DBSA/clay systems. The interaction between the intercalated PAN-DBSA and the clay layers was observed by FT-IR spectra. The results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) showed the improved thermal stability of the nanocomposite materials. The sigma(dc) of these systems was 10(1)-10(-2) S/cm at room temperature, varying with dopant molar ratio. The sigma(dc)(T) of the nanocomposite of PAN-DBSA/clay was represented by the quasi-one-dimensional variable range hopping model. From electron paramagnetic resonance experiments, magnetic susceptibility was obtained for the systems. We discuss the effects of the intercalation and clay on charge transport, structural, and thermal properties for PAN-DBSA/clay nanocomposites.