Through a mild thermal precipitation and aging process, hydrated cobalt oxalate nanorods were synthesized using CoSO3 and (NH4)2C2O4·H2O as raw materials at the reaction and aging temperature of 65 °C. Afterwards, the metal cobalt nanofibres were prepared by decomposition of cobalt oxalate nanorods precursor in Ar gas atmosphere. The composition and morphology of products were characterized by means of atomic absorption spectrometer (AAS), organic elemental analyzer (OEA), Fourier transform infrared spectroscopy (FT-IR), thermogravimetry analysis and derivative thermogravimetry (TGA-DTG), the X-ray diffraction (XRD), and scanning electron microscope (SEM). The results demonstrate that the product is hydrated cobalt oxalate, and the chemical formula CoC2O4·3H2O is confirmed. The sizes of the cobalt oxalate nanorods as-prepared are about 0.2-0.4 μm in diameter, and 1.0-5.0 μm in length; the metal nanofibres prepared via decomposition process of hydrated cobalt oxalate nanorods are about 0.2 μm in diameter, and 1.0-5.0 μm in length.