Ternary Al-Ca-Ti alloy samples and diffusion couples Al2Ca-Ti were investigated using scanning electron microscopy with energy dispersive X-ray spectroscopy, X-ray powder diffraction, and metallographic analysis. The experiments turned out to be very difficult, as expected by this combination of elements, and adapted techniques were used. The results indicate that ternary solubilities of Ca in Al-Ti phases were not observed and no ternary phase was found in the ternary mid-composition range. The binary Ca-Ti and the ternary Al-Ca-Ti phase diagrams are developed for the first time. They are based on consistent thermodynamic calculation by combining the binary edge systems and incorporating the Al-rich Al20CaTi2 phase.