Uniaxially aligned mullite ceramic fibers were prepared by electrospinning a polyacrylonitrile/mullite sal mixture with a rotating drum simultaneously acting as a collection device followed by sintering. A novel mullite precursor sol was synthesized using N,N-dimethylformamide as a solvent. The mean diameter of the mullite sol particles was 15.6 +/- 5.7 nm. The crystal development and micromorphological evolution of both the as-electrospun composite fibers and the sintered mullite fibers were investigated by scanning electron microscopy, X-ray diffractometry, thermogravimetry-differential scanning calorimetry, and Fourier transform infrared spectroscopy. The sintering temperature played an important role in controlling the surface morphology, diameters, and crystal structure of the mullite fibers. Upon sintering the composite fibers at 1000 and 1300 degrees C, metastable tetragonal phase mullite and stable orthorhombic phase mullite fibers were obtained. (C) 2014 Elsevier B.V. All rights reserved.