Densities at high pressures for the binary mixture of methylnonafluorobutyl ether + hexane were measured, as well as those corresponding to both pure fluids, in a pressure range from (0.1 to 25) MPa and at temperatures of (283.15, 298.15, and 313.15) K. A vibrating tube densimeter connected to a high-pressure measuring cell was used for the density determination. Experimental data for the mixture were fitted using a modified Tait equation. From this set of experimental data, excess molar volumes of the mixture were calculated and then correlated using a temperature- and pressure-dependent modified Redlich-Kister equation.