A comparative corrosion behaviour of Al-Cu based LM13 alloy, LM13-10%SiCp composite and cast iron has been evaluated in 3.5% NaCl solution using electrochemical measurements and surface studies. It is found that the base alloy shows better corrosion resistance than composite, whereas cast iron exhibits comparatively poor corrosion resistance. Presence of alumina film on the base alloy and the composite increases their corrosion resistance up to certain level. Electrochemical impedance spectroscopy measurement indicates that charge transfer reaction related to diffusion of chloride ions proceeds through the oxide/solution interfaces in the beginning. This increases with the increase in exposure time. Microstructural study of the corroded surfaces suggests the occurrence of the galvanic corrosion to the base alloy and the composite and graphite corrosion to the cast iron.