Composites of polyaniline (PANI) with both conducting and ferromagnetic feature were synthesized by an improved method proposed by the authors. The electrical and ferromagnetic properties of the composites were measured as a function of the concentration of KOH solution used during polymerization. The conductivity of the composites at room temperature decreases with the increase of the concentration of KOH; the maximum conductivity of 8.0 x 10(-1) S/cm can be obtained when 25 wt % of concentration of KOH was used. For a high concentration of KOH, ferromagnetic properties of the composites including a high saturated magnetization (similar to 10.0 emu/g) depending on the concentration of KOH solution and a lower coercive force (H-c approximate to 0) independent of the concentration of KOH solution were observed. It has been demonstrated that magnetic particles (Fe3O4) with nanometer size in the composites can be attributed to the ferromagnetic properties of the composites observed. For a lower concentration of KOH solution, on the other hand, the magnetic properties of the composites can be decomposed to Curie susceptibility chi(c) depending on the temperature and Pauli susceptibility chi(P) independent of the temperature.