Nanoscopic conducting polypyrrole powder was prepared in an oil/water microemulsion with FeCl3 as a dopant. Compared with solution and conventional emulsion polymerizations, a microemulsion polymerization system increases the yield of the resultant polypyrrole. The results of FTIR spectra and thermal analysis studies indicate that the microemulsion polymerization system increased the extent of the pi-conjugation length along the polymer backbone and ordered the arrangement of the macromolecule chains. These two effects bring about enhanced conductivity as well as higher thermal stability of polypyrrole.