The precipitation of α phase during ageing was investigated in the near-β titanium alloy Ti-17 considering either a fully β_metastable initial microstructure or a 35% α_primary + 65% β_metastable initial microstructure. In-situ electrical resistivity and high energy X-ray diffraction measurements revealed the influence of the initial microstructure, with different α morphologies (size and distribution of α_primary), as well as the heating rate on the precipitation sequences and kinetics following the decomposition of the β-metastable phase. Various amounts of metastable phases (ω_isothermal and α″_isothermal) precipitate in temperature ranges that increase with the heating rate. From temperatures about 500 °C, the orthorhombic α″_isothermal structure evolved towards the hexagonal close-packed α as temperature increased. SEM microstructure characterisations showed that slow heating rates promoted a fine and dense α precipitate distribution through the formation of ω_isothermal and/or α″_isothermal, leading to higher hardness values. A higher heating rate restricted the precipitation of α″_isothermal and shifted to the one of α at a higher temperature, leading to coarser precipitates. Furthermore, precipitation kinetics of α″_isothermal/α were quicker considering an initial intragranular α precipitation as compared to α colonies.