The solidus and the liquidus of U-Zr system were determined using the “spot-technique” over the entire composition range. The experimental facility was fabricated in-house and installed in a glove box for investigating solid to liquid phase transitions in radioactive alloys. This equipment is capable of operating in the temperature range 1273–2273 K. U-Zr alloys of desired composition were prepared by arc melting the constituent elements in required proportion. These alloys were heated by radiofrequency (RF) induction under vacuum and the change in their optical reflectivity was monitored. Chemical analyses of U-Zr alloys indicate that the uncertainty in the composition is ±1.3 at.% Zr (max.). The accuracy of the temperature measurement was ascertained by measuring the melting points of high purity Au, Cu, Ni and Zr. The measured values of the melting points were accurate within ±3 K. This is the first time that the solidus and the liquidus of U-Zr system were determined by using a single experimental technique over the entire composition range. © 2016 Elsevier B.V.