Solid-liquid interactions are central to diverse processes. The interaction strength can be described by the solid-liquid interfacial free energy (${\gamma }_{\mathrm{SL}}$), a quantity that is difficult to measure. Here, we present the direct experimental measurement of ${\gamma }_{\mathrm{SL}}$ for a variety of solid materials, from nonpolar polymers to highly wetting metals. By attaching a thin solid film on top of a liquid meniscus, we create a solid-liquid interface. The interface determines the curvature of the meniscus, analysis of which yields ${\gamma }_{\mathrm{SL}}$ with an uncertainty of less than 10%. Measurement of classically challenging metal-water interfaces reveals ${\gamma }_{\mathrm{SL}}\sim 30–60\mathrm{mJ}/{\mathrm{m}}^2$, demonstrating quantitatively that water-metal adhesion is 80% stronger than the cohesion energy of bulk water, and experimentally verifying previous quantum chemical calculations.

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• Elemental metals
• Liquid-solid interfaces
• Surfaces
• Water
• Tension tests