Metal silicide intermetallic compounds are promising electrocatalysts for the Oxygen Evolution Reaction (OER) due to their exceptional oxidation resistance. While nickel silicides synthesized at ambient pressure have demonstrated remarkable catalytic performance, this study aims to leverage the structural diversity of these materials under high-pressure (HP) conditions to develop novel HP metal silicides with potential applications in electrocatalysis. Focusing on the Ni-Si system, we will employ in situ X-ray diffraction (XRD) with a multi-anvil press (up to 15 GPa) to monitor synthesis in real time. The main objectives are to (1) synthesize CsCl-type NiSi structures, (2) investigate the impact of particle size on phase transformations, and (3) explore the high-pressure phase transitions of Ni₂Si (up to 15 GPa), which remain uncharted in the literature.