Excess molar volumes at 298.15 K are reported for the binary systems containing toluene, p-xylene or pseudo-cumene +2-propanone, 2-butanone, 2-pentanone, 2-octanone or 2-undecanone. All experimental curves present negative excess volumes, with the sole exception of the pseudo-cumene(1) +2-propanone(2) mixture. The experimental data are examined by an extended cell model.