The electrodeposition of nickel was studied using electrochemical techniques in different electrolytes and various agents. The voltammetry analysis clearly showed that the electrodeposition of nickel was a diffusion-controlled process associated with a typical nucleation process. The current transients represented instantaneous nucleation with a typical three-dimensional (3D) growth mechanism. Scharifker's equations were derived for instantaneous and progressive nucleation of the 3D growth of the spherical centers under diffusion-controlled condition. The number of nucleation sites increased with the increment in overpotential and Ni2+ concentration. Atomic force microscopy was used to confirm the presumed model. Also, the electrocatalytic activities of the Ni films were investigated for hydrogen evolution reaction (HER). The electrocatalytic activity of the Ni nanostructure was three times higher than the 2D Ni microstructure when the overpotential of -1.2 V was applied. The HER current density at -1.4 V for Ni nanostructure (-20 mA cm(-2)) was considerable with respect to the Ni microstructure (-8.46 mA cm(-2)) too.