The high-temperature phase relations in the system Ce2O3-Ce2Si2O7 have been studied in the temperature range 1150 degrees-1970 degrees C in inert and reducing atmospheres by conventional quenching and differential thermal analysis. Three eutectic reactions were found to occur at 1664 degrees C and 27 mol% SiO2 between Ce2O3 and Ce2SiO5, at 1870 degrees C and 54 mol% SiO2 between Ce2SiO5 and Ce-4.67(SiO4)(3)O, and at 1762 degrees C and 65 mol% SiO2 between Ce-4.67(SiO4)(3)O and Ce2Si2O7. Microstructural characteristics of the eutectic reactions mere observed. Cerium pyrosilicate exhibits a polymorphic transformation at 1274 degrees C. The binary compounds of this system were all found to melt congruently. The enthalpy and entropy of melting of these binary compounds mere calculated from the initial slopes of their experimentally determined liquidus lines.