Excess molar volumes V-E of diisopropyl ether + butanoic acid and + butyl formate were measured at pressures of 0.1 MPa, 20 MPa, 40 MPa, and 60 MPa and at temperatures of 278.15 K, 298.15 K, and 323.15 K. V-E is negative for all the mixtures studied over the whole concentration range and for all temperatures. Results were correlated by polynomial equations of the type V-E = x(1)x(2) Sigma(i)A(i)(2x(1)-1)(i).