Experimental investigations of the C-v,C-x, P, V, T properties in the n-hexane-water system with the different compositions (x) 0.121, 0.200, 0.247, 0.256, 0.301, 0.345 and 0.615 molar fraction (m.f.) H2O were made with a high-temperature adiabatic calorimeter. The mixtures with 0.256 and 0.615 m.f. H2O were studied over the wide range of densities (rho) from 208.6 to 399.6 kg m(-3) and from 191.4 to 416.7 kg m(-3), respectively. For the description of some of the thermodynamic properties of the n-hexane-water binary system, the equation of state proposed by Jin et al. was used.