We have developed a method for predicting solid-liquid interfacial tension based on density functional theory and the implicit solvent model COSMO-RS. Our model takes into account the solvation contributions and can be used to predict wetting behavior for a solid surface in contact with two liquids. We benchmarked our model against measurements of contact angle from water-in-oil on silica wafers and a range of self assembled monolayers (SAMs) with different composition, ranging from oil-wet to water-wet. By explicitly including deprotonation for the silica surfaces and carboxylic acid self-assembled monolayers, very good agreement was obtained with experimental data for all surfaces. Solid-liquid interfacial tension cannot be measured directly, making predictions such as from our model all the more important.