The liquidus of the binary system (Cu2O + CaO) has been experimentally investigated over the temperature range from (1050 to 1500) degrees C in air. The liquidus has been quantified by the equilibration/quench/analysis technique. Equilibrated specimens were quenched in brine solution of 10 wt% NaCl. Specimens were then examined by Energy-Dispersive X-ray Spectroscopy (EDS) and Electron probe micro-analyzer (EPMA) to quantify liquid chemical compositions. This work reveals that the solubility of CaO in the liquid phase of the binary (Cu2O + CaO) at higher temperatures is lower than previously reported, and the deviation systematically increases with a corresponding increase in temperature. This is predominant at temperatures between (1300 and 1500) degrees C where a deviation of up to 5 wt% in CaO solubility is observed. The solubility of Cu2O in liquid phase for the cuprite saturated section of the binary however is consistent with all the previous authors. (C) 2014 Elsevier Ltd. All rights reserved.