Unlike conventional electrospun polymer fibers deposited on a target electrode as a randomly oriented mesh, poly(p-xylenetetrahydrotbiophenium chloride) was electrospun into centimeters-long yarns vertically on the surface of the electrode but parallel to the electric field. The diameter of the yarn was strongly affected by the concentration, spinning rate, and viscosity of the polymer solution, but less dependent on the applied voltage. The subsequent carbonization of thus-electrospun yarns at 600-1000 degrees C resulted in uniaxially aligned carbon nanofibers with average diameters of 127-184 nm. On the basis of Raman spectra, the graphitic crystallite size and the molar fraction of graphite were estimated to be 1.2-1.4 and 0.21-0.24 nm, respectively. (C) 2007 Wiley Periodicals, Inc.