The effect of pressure on the volume of five mixtures of (butan-2-one + 2,2,4-trimerhylpentane) has been measured with a bellows volumometer at six temperatures (T/K = 278.15, 288.15, 298.14, 313.14, 323.14, and 338.13) up to a maximum pressure of about 380 MPa. The results have been represented by equations which enable calculation of thermodynamic quantities and interpolation of the volumetric data as a function of pressure or temperature. Densities have been determined at p = 0.1 MPa over the whole composition range at each temperature. The results have been used to calculate isothermal compressibilities, isobaric expansivities, excess molar volumes, and changes due to pressure in the excess molar Gibbs free energy and enthalpy.