The effect of hot-pressing and annealing on precipitation in a Ti-9 wt% Mg alloy solid solution produced by quenching from the vapour phase is described. Precipitates about 20 nm diameter and over 100 nm diameter were found within the grains and at grain boundaries, respectively, after hot pressing at 500-600 degrees C. Using electron diffraction contrast imaging, selected area electron diffraction, Moire fringe analysis and energy dispersive X-ray spectroscopy, the particles were identified as Mg. The negligible solubility of Mg in Ti led to exceptional resistance to Mg particle coarsening at temperatures up to 960 degrees C in the Ti beta-phase field.