The present work focuses on the effect of Ni content (0, 5, 10, and 30 %) on the corrosion behavior of Cu-10Al-xNi ternary alloys in Na2SO4 solutions. The electrochemical properties were investigated in Na2SO4 solutions by polarization measurements, cyclic voltammetry and electrochemical impedance spectroscopy, EIS, techniques. Surface examination and morphological studies were employed. The results show that the addition of Ni to Cu-Al alloys increases the corrosion resistance. Also, the increase in the Ni content improves the corrosion resistance of the Cu-Al-Ni ternary alloys due to formation of a stable passive film. The mechanism of the corrosion process and the barrier film formation was discussed. The experimental EIS data were fitted to the theoretical data according to the suggested model. The incorporation of Ni in the cuprous oxide (Cu2O) barrier film leads to its stabilization. An equivalent circuit model for the electrode/electrolyte interface under different conditions was proposed. For industrial applications, the results lead to the recommendation of the Cu-10Al-30Ni alloy for applications in the production of Na2SO4.