Experimental densities for the compressed liquid phase are reported for dimethyl carbonate and octane, and nine of their mixtures over the composition range (0.1 less than or equal to x less than or equal to 0.9), the temperature range 278.15-353.15 K and for pressures up to 25 MPa. Density values (725 experimental data) of this system have been measured with a high-pressure vibrating tube densimeter, with an uncertainty of 3 x 10(-5) g cm(-3). Moreover, we present a new calibration of this apparatus for this range of pressure and temperature by using the method of Lagourette et al. Data reliability has been verified by comparing our experimental results for octane, dichloromethane and dimethyl carbonate with literature data. For each composition, the experimental values were correlated using a Tait-type equation. Furthermore, the isothermal compressibilities, isobaric thermal expansion coefficients and internal pressures have been calculated using the Tait correlations.