Aluminium alloys are susceptible to corrosion due to microgalvanic coupling of the Al matrix and intermetallic particles (IMP). Among different protection strategies, conversion coatings can be selectively deposited on more noble sites. Cerium conversion coatings (CeCC) have been proven to inhibit the cathodic reaction by preferentially depositing on the cathodic IMP. Their spontaneous deposition achieved by immersion of aluminium substrate in Ce-ion containing baths is a consequence of the localised pH increase because of oxygen reduction reaction at local cathodic sites of the microstructure. The influence of bath process parameters (like cerium salt type, cerium ion concentration, pH etc.) have been widely investigated primarily on AA2024 and AA7075, but the more general role of microstructure remains to be clearly understood. Due to the localised nature of deposition reactions, the microstrucutre, in the sense of chemical composition, size and distribution of the second phase or IMP play a crucial role in the deposition behaviour. This research investigates the role of IMP size and distribution in the microstructure, i.e. how far or close they are spaced from each other, on the deposition of CeCC. Two model cast Al-7wt.% Si alloys are selected with 2wt.% Cu and 1wt.% Fe respectively. Different IM distribution in the microstructure is achieved by implementing slow and fast cooling rates for solidification of these hypoeutectic Al-Si alloys. CeCC coatings are spontaneously deposited by immersion in cerium chloride salt solutions. Bare metal and CeCC deposited microstructure is characterized with optical microscopy, scanning electron microscopy and energy dispersive x-ray spectroscopy.