A 3D continuum code coupled with a kinetic Monte Carlo module has been developed for the simulation of Ni electrocrystallization in the initial stages of nucleation and growth. Mass transfer in solution was controlled by a finite-difference code which is distributed over an irregular nanoscale grid system in vertical direction to the substrate. Deposition events such as surface diffusion, chemisorption and crystallization in the system were considered in a KMC module that processes the output of a diffusion-controlled scheme in probability functions to model electrodeposition process on surface. Electrochemical data of this simulation was simultaneously generated according to analytical electrochemical equations to study nucleation and growth mechanism. In spite of minor dissimilarities at current transient coordinates, a reasonable agreement could be noticed between electroanalytical simulation data and experimental results, both of which showed that under presumed conditions nickel electrodeposition is prone to a progressive nucleation mechanism at initial seconds. A similar result has been achieved from the juxtaposition of experimental morphological studies and simulated snapshots. It was found that a balance between surface diffusion and charge transfer reaction rate is a critical factor in dominant nucleation mechanism and deviation from the equilibrium could remarkably alter the nucleation regime and also nanostructure of the deposit. (C) 2017 Published by Elsevier Ltd.