A solution of a polyimide (PI, Matrimid® 5218) in dimethylacetamide was electrospun, and carbonization of the electrospun nonwoven fabrics produced carbon nanofiber fabrics. The effects of iron(TIT) acetylacetonate (AAI) on carbonization and the resulting morphology were also investigited. The carbonization behavior of the nonwoven fabrics was examined by X-ray diffraction and Raman spectro copy. AAI promoted carbonization of the nonwoven fabrics and increased the carbon yield. Addition of 3 wt % AAI increased the crystal dimension of electrospun PI nanofibers from 1.06 to 4.18 nm and decreased the integrated intensity ratio front 3.37 to 1.83 when heat treated at 1200° C. Scanning electron microscopy images of the carbonized nonwoven fabrics showed that AAI remained as particles within the fibers after carbonization. In addition, transmission electron microscopy observations revealed that turbostratic-oriented graphite layers were observed around the particles even at 1200° C, which have been reported only on carbonization of rigid-chain solvent insoluble PI materials under tension. © 2005 Wiley Periodicals, Inc.