An hydration scale (W0) for aqueous sulfolane and dimethyl sulfoxide (DMSO) has been developed that represents the effect of the solvent on the equilibrium hydration of a series of trifluoroacetophenones; [Formula: see text]. The equilibrium constants are correlated with the substituent parameter σ+; ρ+ = −1.62 for dehydration. The function W0, defined as [Formula: see text] is zero for pure water and rises to a value of 2.72 in 99 mole% sulfolane. W0 in aqueous DMSO is negative from 0 to 85 mole% DMSO, meaning that these systems hydrate the ketones to a greater extent than does pure water.