Graphite fibers were developed from polyacrylonitrile (PAN) fibers which were modified with potassium permanganate. After the transitional temperature, the formation of graphite structures commenced, the crystals increased in thickness, and the preferred orientation of the fiber crystals increased. The Raman specific absorption peak of noncrystalline carbon layers (1360 cm−1) weakened with the increase in the graphitization temperature, whereas the degree of graphitization rose. The results of this analysis indicate that manganese has the effect of catalyzing graphitization, thus increasing the mechanical properties of the graphite fibers. © 1996 John Wiley & Sons, Inc.