Ternary vapor-liquid (VLE), liquid-liquid (LLE) and solid-liquid-liquid (SLLE) equilibria of ethanol-water and tetrahydrofuran (THF)-water solutions containing different kinds of hyperbranched polymers are presented. For the system THF-water-hyperbranched polyester a remarkably distinct solutropic phenomenon is observed. Commercially available hyperbranched polyesters and hyperbranched polyesteramides are found to be capable of breaking the ethanol-water and THF-water azeotrope. The experimental results underline the potential of hyperbranched polymers in the field of process engineering, especially as an entrainer for extractive distillation and as selective solvents for solvent extraction. The non-volatility of hyperbranched polymers in combination with their remarkable separation efficiency and selectivity enables new processes for the separation of azeotropic mixtures. The separation approaches proposed might offer a potential for cost-savings in comparison with conventional separation processes. (C) 2002 Elsevier Science B.V. All rights reserved.