Nickel nanopowders are obtained by the spark discharge method, which is based on the evaporation of the electrode surface under the action of the discharge current, followed by vapor condensation and the formation of nanoparticles. Nickel electrodes with a purity of 99.99% are used to synthesize the nickel nanoparticles in the setup. Nitrogen is used as the carrier gas with a purity of 99.998%. XRD, TEM, and EDX analyses of the nanopowders are performed. Moreover, HRTEM images with measured interplanar spacings are obtained. In the nickel nanopowder samples, a phase of approximately 90 wt% with an expanded crystal lattice of 6.5% on average is found. The results indicate an unusual process of nickel nanoparticle formation when the spark discharge method is employed.