AluminumAluminum (Al) alloys are known for their high strengthStrength-to-weight ratio, good thermal conductivity, and cost-effectiveness, making them suitable for heat exchangerHeat exchangers applications. However, most commercial Al alloysAl alloys exhibit limited thermal stabilityThermal stability at elevated temperatures (>200 °C). The binary Al-Ca system has lower density than pure aluminumAluminum and shows promising thermal stabilityThermal stability at elevated temperatures. Here, we investigate the ternary Al-Ca-Ce alloy system, which has not been studied extensively, as a potential candidate for high-temperature applications. We characterize the phases present, and find Al4(Ca, Ce) and Al11(Ce, Ca)3 intermetallicIntermetallics compounds, with mutual solid solubility of Ce and Ca in their respective phases. Al4Ca is monoclinic at room temperature in binary Al-Ca and tetragonal at high temperatures; in Al-Ca-Ce, the Al4Ca phase is tetragonal at room temperature. We further investigate the influence of this mutual solubility on the coarsening behavior and thermal stabilityThermal stability of the ternary Al-Ca-Ce alloy system via ageing treatments at 250 and 400 °C. HardnessHardness measurementsMeasurements confirm that addition of Ce to a hypo eutecticEutectic Al-Ca alloy is not detrimental to the coarsening behavior of Al-6Ca (wt.%).