Experimental densities (ρ) and ultrasonic sound velocities (u) for the binary mixtures of toluene, o-chlorotoluene, m-chlorotoluene, and p-chlorotoluene with 1-octanol were measured over the entire composition range at T = (298.15, 303.15, and 308.15) K and at a pressure of 0.1 MPa. Excess volumes (V E), isentropic compressibilities $$ (\kappa_{\text{s}} ) $$ ( κ s ) , and excess isentropic compressibilities $$ (\kappa_{\text{s}}^{\text{E}} ) $$ ( κ s E ) were calculated using the measured experimental densities and ultrasonic sound velocities of the pure liquids and their mixtures. The experimental data were discussed in terms of intermolecular interactions between component molecules. The measured excess properties were correlated with the Redlich–Kister polynomial equation.