<p>Nickel-copper alloy coating is a promising approach for surface modification due to its functional properties, including corrosion resistance, enhanced catalytic activity, and decorative finishes. The morphology and composition of the coating play a crucial role in its optimal performance. This study investigates the co-electrodeposition of Ni-Cu alloy coatings under different pH values, current modes, and additive conditions. The reduction mechanism was analyzed using cyclic voltammetry (CV), while scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were employed to appraise the coating’s morphology and the elemental composition, respectively. Cyclic voltammetry revealed that citrate, as a complexing agent, induces a cathodic shift in the reduction potentials of Cu²⁺ and Ni²⁺ ions. However, saccharin adsorption partially mitigates this effect and increases hysteresis, suggesting surface modification and altered electron-transfer kinetics. The extent of hysteresis intensified with pH, attributed to the formation and stabilization of surface hydroxide/oxide layers under alkaline conditions. Deposition rate measurements showed that acidic conditions favor higher growth rates, whereas pH 9 and pulsed modes exhibited lower rates, likely due to surface passivation and diffusion limitation, respectively. Morphological analysis revealed that coating under pulsed current, especially with a duty cycle of 90%, exhibited microcracks, whose distribution and length depended on the electrolyte pH. The incorporation of saccharin refined the grain structure, reduced crack density, and yielded more uniform dense films. Elemental analysis confirmed that the Cu/Ni ratio increases with pH, reflecting the preferential deposition of copper in alkaline media. Overall, these findings demonstrate how electrolyte chemistry, current modulation, and additive adsorption jointly influence nucleation, stress evolution, and final coating quality in Ni-Cu alloy electrodeposition.</p>