Mesophase pitch nanofibers, made by a recently patented nanofiber processing technology, were stabilized, carbonized and graphitized to study the formation of novel carbon and graphite nanofibers. These pitch nanofibers were birefringent, and had diameters as small as 100 nm. Thermogravimetric analysis showed the pitch nanofibers could be stabilized in air, and the air stabilization resulted in ca. 6 % weight gain, due to the absorption of oxygen. Air stabilization eliminated aromatic and aliphatic C—H structures, and created carbonyl and aryl/alkyl ether structures. After stabilization, the pitch molecules were crosslinked which prevented the nanofibers from melting during subsequent carbonization. Carbonization of the stabilized pitch nanofibers occurred in inert gas, and carbonization caused ca. 23 % weight loss. During carbonization, the stabilized nanofibers underwent cyclization and evolved volatile molecules such as H2O, H2, HCN, N2 and others. Carbonization generated carbon basal sheets, and the carbon basal sheets grew larger and became more oriented with the increasing of carbonization temperature. Further graphitization of the carbonized pitch nanofibers with the temperature up to 2200°C resulted in the formation of highly ordered graphitic sheets. The normals to the sheets were perpendicular to the fiber axis, which implied the graphite nanofibers were mechanically strong. The morphological, chemical and structural properties of the as-made pitch nanofibers as well as the concomitant stabilized, carbonized and graphitized nanofibers were characterized by SEM, TEM, FT-IR and XRD.