The electrochemical corrosion behaviour of electrodeposited Ni–Al composite coating, containing 1?m–size Al particles, was studied in 3.5% NaCl + 0.05 M H2SO4 solution using electrochemical and surface probe techniques. Open circuit potential measurement revealed that the Al particles shift the Ni corrosion potential to more negative regions. Potentiodynamic polarization characterization showed that the Al particles increase the corrosion rate of the Ni coating by increasing both cathodic and anodic half–reactions. XPS characterization confirmed that the Al corrosion products are highly dissoluble in the 3.5% NaCl + 0.05 M H2SO4 solution. This dissolution disturbs the easy linkage of the Ni corrosion product based on SEM characterization.