Relative permittivity and density measurements at atmospheric pressure of {dimethyl carbonate or diethyl carbonate} + n-dodecane mixtures have been carried out in the temperature range of 288.15 K to 328.15 K. Measurements have been performed scanning the entire composition range of mixing and the variations of the relative permittivity values and the excess molar volumes have been calculated. These values have been correlated by Redlich-Kister equation. Also, the density and the excess molar volumes for both mixtures have been fitted as a function of the mole fraction and temperature. Different mixing rules have been applied to predict the permittivity values and the results indicate that the predictions are better when the volume change on mixing is incorporated in the calculations. (C) 2004 Elsevier Ltd. All rights reserved.