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Abstract Supercritical carbon dioxide (sCO2) power cycles are promising next-generation technologies for applications in concentrated solar power, fossil fuel plants, geothermal electricity, nuclear power, and ship propulsion. However, sCO2’s successful application in nuclear systems (specifically at 350–700 °C and 20–35 MPa) would hinge on overcoming important issues, such as the high leakages in turbomachinery seals. To mitigate this, we developed and experimentally validated a novel EHD shaft end seal in static conditions. The seal operates through pressure-induced deformation, whereby inlet pressure compresses a flexible sleeve to restrict the flow path, reducing leakage without metal-to-metal contact. A static test rig was constructed to test fluid leakage with nitrogen gas. The test seal, made of carbon graphite, was paired with a 50.8 mm diameter steel shaft. Tests were performed with an initial clearance of 25.4 μm, while inlet pressure was gradually increased up to 8.85 MPa. The maximum recorded leakage rate was 4 g/s at 3.5 MPa. However, as pressure increased to 8 MPa, leakage dropped to 0.5 g/s, forming a bell-shaped curve. At a 95% confidence level, the estimated confidence intervals for the mean leakage rates were ±0.12 g/s at 3.5 MPa and ±0.09 g/s at 8 MPa, confirming the throttling effect. The seal’s performance was also simulated using fluid-structure interaction (FSI) physics in COMSOL Multiphysics software, which confirmed key experimental trends. These results suggest that EHD seal can potentially minimize leakage and enhance efficiency in sCO2 turbomachinery applications.