Cast aluminum alloys have seen extensive service in marine applications where good mechanical properties and better resistance to corrosion are desired. These properties are ideal for components of novel tidal-based energy generating systems. In this study the effects of dissolved oxygen and temperature on the microstructure and electrochemical behavior of B206 and A356 aluminum alloys were investigated in artificial and real seawater for possible use in this energy generation application. This investigation was carried out through the analysis of potentiodynamic polarization curves at temperatures ranging from 6 to 25 °C. The morphology and composition of the corrosion products were analyzed using scanning electron microscopy (SEM) and X-ray diffraction (XRD). Variations in temperature both in the absence and presence of oxygen have little effect on corrosion behavior. Therefore the effect of dissolved oxygen on the corrosion behavior is stronger than that of temperature.