This work investigates the dehydrogenation of TiH2 powder during isothermal heating at 600°C using the static x-ray scans of high temperature x-ray diffraction (XRD). As-received TiH2 powder with a particle size of 5 μm and purity of 99.1% was used for this measurement. With increasing temperature, phase transformations occurred because of dehydrogenation and it happened very fast. It was found that during the phase transformation of TiH2 to titanium, some transitional phases observed and occurred. This finding confirmed the in-situ determination of TiH2 powder dehydrogenation by using Rietveld Refinement Method from our previous research. This study is useful for the fabrication of titanium-based composites and titanium alloys from TiH2 powder because the different phases in TiH2 will affect the final mechanical properties in titanium.