This book presents the design and structural analysis of a hydraulic compression support system developed for a Proton Exchange Membrane (PEM) electrolyzer stack. The system is designed to apply uniform, controllable compressive loads up to 75 tonne using a hydraulic jack and oil tank assembly mounted on a structural steel frame. Finite Element Analysis (FEA) was conducted to evaluate stress and deflection behaviour at different load cases. The results confirmed that the structure, fabricated with E250 grade steel, provides sufficient strength, stiffness, and safety for PEM stack compression...