The phase equilibria of the binary Ce–Zr system have been investigated between 900K and 1800K by a combining conical nozzle levitation technique with in situ high energy synchrotron X-ray diffraction. From the diffraction data the phase sequences and the liquidus line were determined experimentally. The Ce–Zr system is an eutectic type. The eutectic reaction L↔bcc-Ce+hcp-Zr occurs at T=1113±5K at the eutectic composition of 1.5±1 at% Zr. Based on the experimental data a self-consistent thermodynamic description of Ce–Zr phase diagram is derived.