Nickel nanoparticles have been synthesized using nickel nitrate, vegetable oil and sucrose. Ethanol has been used as a solvent since the heat of reaction shows the destabilization of nickel particles if water is present in the synthesis mixture. Nickel with fcc phase is obtained by reduction with sucrose followed by stabilization using vegetable oil. Nickel or possibly nickel carbide with hcp structure is obtained by treatment with a mixture of oleylamine and methanol. The fcc and hcp crystal structures have been characterized by XRD. The calcination of nickel nanoparticles at 450 °C results in the sintering of nickel nanoparticles, thereby increasing the crystallite size. The scanning electron micrograph reveals that the particle size is in the range of 5 - 58 nm for fcc-Ni nanoparticles calcined at 450 °C for 10 min.