The utilisation of TiH2 powder in titanium and its alloys sintering has been receiving increasing interest. This study presents an in situ observation of phase transformation in blended TiH2 and Ni powders sintering using neutron diffraction. Densification and microstructure of the as-sintered NiTi alloy, and the hydrogen release during sintering is reported. The sintering mechanism involving the use of TiH2 is discussed for synthesizing NiTi shape memory alloy. The sintered porous alloy has 26.9 % open porosity and exhibits volumetric shrinkage. The predominant phase identified in the produced NiTi alloys sintered at 1373 K is B2 NiTi phase with the presence of other minor phases.