In many studies, solvent additives have been reported that enhance reactions or separations in a supercritical fluid process. In this work, a strategy is proposed for using solvent-pair mixtures that relies on combining hydrogen bond donor (HBD) and acceptor (HBA) molecular solvents and considering their Kamlet-Taft (KT) parameters. An overview of solvents and solvent mixtures in terms of their KT-parameters is given. The strategy of using HBD-HBA solvent-pairs with supercritical fluids is applied to extraction and separations, thin-layer and flash chromatography, and technological areas in carbohydrate conversion, exfoliation, expanded liquids, polymer deposition, particle formation, nanoparticle stability and solar cell recycle. Favorable non-aqueous HBD-HBA solvent-pairs in some of the applications are ethanol-ethyl acetate, ethanol-acetone and ethanol-acetonitrile. Water-alcohol and water-lactone solvent-pairs are useful when aqueous mixtures are required. Changes in the Kamlet-Taft HBD-HBA mixed-solvent KT-basicity with composition is the key to understanding the enhancements obtained in the applications.