[en] The densities of (octane + benzene) were measured at elevated pressures (0.1 to 40) MPa at four temperatures over the range (298.15 to 328.15) K with a high-pressure apparatus. The high-pressure density data were fitted to the Tait equation and the isothermal compressibilities were calculated with a novel computation procedure with the aid of this equation. The low- and high-pressure values of excess molar volume V_m^E calculated from the density data show that the deviations from ideal behaviour in the system are practically independent of temperature and decreases slightly as the pressure is raised. The V_m^E data were fitted to the fourth-order Redlich-Kister equation, with the maximum likelihood principle being applied for the determination of the adjustable parameters