A copper complex of polypyrrole is obtained when the polymer perchlorate is treated with a Cu(II)-containing alkaline solution. The X-ray photoelectron spectrum of the resulting polymer material shows that the copper atoms are coordinated to pyrrole nitrogen. The ESR signal of copper ions and that of the pyrrole rings are observed independently of each other; there is no appreciable magnetic interaction between the two paramagnetic species. The room-temperature conductivity is 4 × 10-4 S cm- and the temperature dependence shows semiconductive behavior with an activation energy of 0.11 eV. The degradation of conducting polypyrrole in aqueous solution is suppressed by the presence of copper: the stabilization is attributed to CuN bond formation.