The in situ polymerization of pyrrole was carried out in the presence of gamma-Fe2O3 to synthesize polypyrrole/gamma-Fe2O3 composites by a chemical oxidation method. The polypyrrole/gamma-Fe2O3 composites were synthesized with various compositions, including 10, 20, 30, 40, and 50 wt % gamma-Fe2O3 in pyrrole. The polypyrrole/gamma-Fe2O3 composites were characterized with X-ray diffractometry and infrared spectroscopy. The surface morphology of these composites was studied with scanning electron microscopy. The direct-current conductivity was studied from 40 to 200 degrees C. The dimensions of the gamma-Fe2O3 particles in the matrix had a greater influence on the conductivity values. (c) 2006 Wiley Periodicals, Inc.