Four different kinds of morphologies including spherical, flowerlike, aristate spherical and linear nanopowders of well-crystalline nickel, have been synthesized by chemical reduction of NiSO4 solution with hydrazine in basic solution. X-ray diffraction (XRD) showed the nickel powder was cubic crystalline, and the average size of the powders ranged from dozens of nanometers to several hundred nanometers, which depended on specific conditions. Field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were employed to examine the as-synthesized Ni nanostructures. The effects of the initial Ni2+ concentration, sodium hydroxide concentration, the aqueous media and surfactant on the morphology have been investigated. The mechanisms for the formation of different morphologies were discussed. In addition, the magnetism properties were characterized through Lake Shore 7410 VSM, and the relationship between morphology and coercivity was also discussed. (c) 2007 Elsevier B.V. All rights reserved.