In-situ time-resolved synchrotron wide-angle and small-angle x-ray scattering (WAXS/SAXS) were conducted to study the homogenization of phase and composition in segregated U-6Nb. The sub-second time resolution data collected during heating to 750 °C and subsequent isothermal holds show that the integrated SAXS intensities correlate well with variations of lattice parameter, solute redistribution, and phase fraction, especially the volume fractions of orthorhombic α-uranium in the segregated alloy. Based on the combined datasets, the phase and compositional homogenization processes within the ∼ 0.01 mm3 volume probed by x-rays are rapid during heating above the monotectoid temperature, completed within approximately 15 s and 60 s, respectively. For the same alloy pre-aged at different time-at-temperatures, our data reveal subtle differences in the time domain for the completion of homogenization, indicating that the initial microstructures of the segregated U-Nb alloys, such as volume fraction of α-U, Nb content in the bcc phase, and possibly the lamellar morphologies, have discernible effects on homogenization. Overall, the present observations provide detailed real-time insight into the homogenization dynamics leading to equilibrium in the high temperature phase.