In this paper, cuprous oxide (Cu2O) nanostructures with different shapes, such as spheres, cubes and rods, have been synthesized by reducing copper nitrate trihydrate with ethylene glycol in the present of poly(vinylypyrrolidone) (PVP). The molar ratio of PVP (in the repeating unit)/Cu(NO3)2 center dot 3H(2)O and reaction temperature have significant effects on the formation and growth of these Cu2O nanostructures. The Cu2O nanorods were fabricated at the molar ratios of PVP/Cu(NO3)(2)center dot 3H(2)O 2-3, while spherical and cubic nanoparticles were formed at the ratios of PVP/Cu(NO3)(2)center dot 3H(2)O 5-7 and 10-15. Increasing with reaction temperatures, monodisperse particles were obtained. The as-synthesized nanoparticles and nanorods were investigated by transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM) and X-ray diffractometry (XRD). With the as-prepared nanoparticles as catalyst, carbon nanofibers (CNFs) were synthesized by catalytic polymerization of acetylene at a lower temperature (250 degrees C). The effects of the catalyst particle sizes on the morphologies of the carbon fibers were studied. (C) 2007 Published by Elsevier B.V.