Submicron-sized Al2O3 fibers were formed by calcination of electrospun aluminum acetate/PVP composite fibers. At 650 degrees C, the fibers were amorphous. As the calcination temperature increased to 750 degrees C, the fibers transitioned from amorphous to 49 % crystalline gamma phase Al2O3. The crystallinity further increased with calcination temperature to 80 % gamma Al2O3 at 950 degrees C, but decreased above 950 degrees C as the crystal structure began to change to alpha phase. The fiber diameters tended to decrease as calcination temperature increased to 950 degrees C but increased as the alpha phase was formed at temperatures above 950 degrees C. Surface areas as measured by BET decreased as gamma phase crystallinity increased. Further decrease in surface area as the gamma phase crystal structure transitioned to alpha phase indicated changing internal pore structures of the fibers.