pvT-properties of binary mixture of 0.977 water + 0.023 n-hexane (mole fraction) have been studied in the temperature intervals from 310 K to 680 K and pressure range up to 60 MPa for 11 values of mixture mean density in a range from 96.96-759.66 kg/m(3) using high-pressure constant-volume piezometer. Lines of phase equilibrium and critical points of the mixture have been determined. The investigation involves dissolution of hydrocarbon in water (L-L transition) and the transition of the hydrocarbon-water solution into gas, including critical and supercritical regions. (C) 2016 Elsevier B.V. All rights reserved.