A new process for the synthesis of metallic Ni, and Ni-Co alloy nanoparticles at a relatively low temperature is reported. The process consists of heating a precursor containing a methyl hydrazine complex of the respective metal ions in nitrogen atmosphere at temperature as low as 400degreesC. The metallic Ni and Ni-Co alloy powders are characterized by scanning electron microscopy, powder X-ray diffraction (XRD), differential thermal analysis (DTA), and thermogravimetric (TG) analysis. The crystalline nanoparticles showed a narrow distribution in the particle size and homogeneous spherical form with mean diameter around 0.40 mum. (C) 2002 Elsevier Science B.V. All rights reserved.