Experimental densities (ρ) and sound speeds (u) have been reported for the first time for the ternary system (propan-1-ol + cyclohexane + benzene) at six temperatures, T = (293.15, 298.15, 303.15, 313.15, 323.15, and 333.15) K, and at atmospheric pressure, covering the full composition range. The corresponding binary subsystems were also studied systematically. From these data, excess molar volumes ( \({V}_{m}^{E}\) ) and excess isentropic compressibilities ( \({\kappa }_{S}^{E}\) ) were derived and correlated using the Redlich-Kister and Cibulka equations for binary and ternary systems, respectively. The composition and temperature dependence of the excess properties provided insight into molecular interactions and structural effects within the mixtures. Densities were modeled with the Perturbed-Chain Statistical Associating Fluid Theory equation of state, while sound speeds were estimated using Schaaff’s Collision Factor Theory and Nomoto’s relation. In addition, the Jouyban-Acree model was applied to represent the composition and temperature dependence of densities and sound speeds, and their related properties, namely thermal expansivities \({\alpha }_{p}\) and isentropic compressibilities \({\kappa }_{S}\) of both binary and ternary mixtures. Ternary excess properties were further compared with values predicted by symmetric (Kohler, Muggianu) and asymmetric (Hillert, Toop) geometric models. The performance of all theoretical and empirical approaches was assessed by statistical indicators, demonstrating their respective strengths and limitations in describing the thermophysical behavior of these complex mixtures.
