Having in mind to produce electrically conductive carbon-epoxy composite materials, we have filled an insulating epoxy resin with an electronic conducting polymer, polypyrrole (PPy). To select the PPy that best suits this process, various PPys were chemically synthesized. The syntheses were performed in water via a dispersion polymerization route using, initially, either FeCl 3 (PPy-Cl Οͺ ) or (NH 4 ) 2 S 2 O 8 (PPy-HSO 4 Οͺ ) as oxidizing agents. Then, using (NH 4 ) 2 S 2 O 8 as the oxidant, two other PPy doped with aromatic species were obtained due to the dissolution of paratoluenesulfonic acid (PPy-TS Οͺ ) or naphtalenesulfonic acid (PPy-NS Οͺ ) in the reaction media. The characterization of the PPy samples by conductivity measurements, together with elemental and thermal analysis, showed that PPy-TS Οͺ exhibits the highest conductivity and thermal stability, with the conductivity remaining steady over 14 days. In addition, a stabilizing effect of the aromatic anions was observed. The experiments have shown that moisture in the PPy cannot be entirely removed and that, with increasing moisture content, the conductivity also increases, indicating an ionic conductivity superimposed on the electronic conductivity usually observed in PPy.