Steel is the backbone of modern civilization. Yet, its significance is accompanied by harmful environmental effects due to the consumption of fossil reductants (coke and coal).In the steelmaking process, using fossil reductants to reduce iron ore leads to 8-10 % of global CO₂ emissions. Hydrogen-based direct reduction (HyDR) is a successful candidate for mitigating CO₂ emissions by steelmaking. Direct reduction is a mature technology that produces sponge iron via natural-gas-based or gasified-coal-based reducing agents that contain H₂. Current technologies are operated at elevated pressures (e.g., MIDREX at 2 bar, HyL/Energiron at 6-8 bar). However, the role of H₂ pressure on the reduction kinetics and microstructural evolution has not been well understood. To understand the influence of H₂ pressure on the reduction kinetics and microstructural evolution of hematite pellets, we performed hematite reduction with pure H₂ at 700 °C with various H₂ pressures, i.e., 1, 10, 50, and 100 bar. The microstructural evolution of pellets was investigated by combining in-situ high-energy X-ray diffraction (HEXRD) and scanning electron microscopy (SEM) equipped with electron backscatter diffraction (EBSD) technique. The obtained results provide new insights into the critical role of hydrogen pressure in the HyDR process.