Abstract Polypyrrole (PPy) of conductivity 10 S cm −1 was synthesized with a MnO 2PyH 2SO 4 system. Epoxy resin-glass fiber (FR-4)-PPy composites with various electrical conductivities were also obtained by controlling the amount of MnO 2 on the surface of the FR-4. By using X-ray diffraction and atomic absorption analysis, we found that MnO 2 functioned as an oxidizing agent in this system and was reduced to Mn 2+. We also found that the dopant ion in PPy was SO 4 2−, using energy-dispersive spectroscopy, electron spectroscopy for chemical analysis, elemental analysis and cyclic voltammetry. With scanning electron microscopy and X-ray diffraction observations, we found that the electrodeposition of copper on PPy proceeded through a propagation process, and its crystal orientation was formed randomly.