In this study a nanocomposite monofilament composed of a nematic thermotropic liquid crystalline polymer (TLCP) mixed with 1.5 wt.% of carbon nanoparticles (CNP) was prepared by melt extrusion. The nanoparticles had either a fibrous (VGCF) or layered (GNP) geometry. The tensile strength and modulus of the fibers increased with the draw down ratio of the filament: a positive effect on the tensile modulus is displayed by fibrous CNP, achieving values higher than those of high property organic fibers utilized as reinforcement for composite materials. Thermotropic transitions were characterized by DSC and in situ synchrotron WAXD. In particular, it was shown that the breadth of the temperature span of the crystalline-nematic transition correlated inversely with the draw down ratio. At high draw down ratio, addition of CNP also increased the relative amount of oriented polymer chains and contributed to sharpening of the mesomorphic transition. (C) 2009 Elsevier Ltd. All rights reserved.