Thermodynamic properties of solid phases in the Cu–O–Al2O3 system were measured by means of the EMF method with oxygen concentration galvanic cells based on stabilized zirconia solid electrolytes. The standard Gibbs energies of formation of pure copper oxides and copper aluminates from their component oxides were determined. Copper aluminates were also investigated calorimetrically by the DSC-TGA combined techniques. Based on the calorimetric measurements, the enthalpies and temperatures of spinel decomposition and delafossite melting were determined. The obtained results were discussed and compared with the available literature data.