Phase transitions in Ti-6Al-4V were studied by means of high-temperature X-ray diffraction using a resistance heated furnace in high vacuum and Cu K sub alpha radiation. The alpha and beta phases could be observed conveniently using the alpha (100), alpha (002) and alpha (101) peaks of the alpha structure and the beta (110) peak of the beta. The phase composition of the sample at selected times and temperatures were determined from spectra recorded in the range of 32-45 deg (2 theta ), the scan time being around 8 minutes. The technique was successfully used to monitor the kinetics of the alpha-to-beta transition during heating and the beta-to-alpha transition during cooling and including the transformation kinetics during isothermal holds