The effect of indium ions on the dissolution of aluminium in chloride solutions as well as the role of impurities normally present were investigated. Electrochemical techniques complemented by SEM and EDAX were utilized for two types of aluminium, Al-I(99.999%) and Al-II(99.61%). The activation process depends on the chloride ion concentration as well as the surface finish of the samples. Activation is attributed to deposition of In at the surface forming In-Al alloy which is responsible for Cl- ion adsorption at high negative potentials (i.e., activation). Deactivation was exhibited in the case of Al-II due to the presence of Fe as an impurity. The effect of addition of Fe3+ alone, and together with In3+, on the activation of Al-I in 0.6 m NaCl was also examined.