Thermodynamic data on liquid mixtures are usually expressed as excess quantities and analysed with the Redlich-Kister equation. Excess molar volume, excess viscosity, excess dielectric constant, and excess Gibbs energy of activation flow are calculated for gamma-butyrolactone (BL) and dimethylcarbonate (DMC) mixtures at T = 298.15 K and atmospheric pressure over the complete composition range. All these excess thermodynamics functions shows that DMC is less associated than BL and the interaction between pairs of like molecules is stronger than between pairs of unlike molecules.