The isentropic compressibilities, speed of sound deviations and changes of isentropic compressibilities of the ternary system 2-propanol + acetone + cyclohexane and the corresponding binary mixtures 2-propanol + acetone, 2-propanol + cyclohexane and acetone + cyclohexane have been evaluated from experimental densities and speed of sound in the complete composition range at 298.15 and 313.15 K. These properties are used to discuss the nature and the extent of intermolecular interaction in the ternary and the constituent binary mixture. Speed of sound deviations, Deltau, changes of isentropic compressibilities, deltakappa(s), have been calculated and fitted by the Redlich-Kister equation for the binary mixtures, while the equation of Cibulka was used to fit the values related to the ternary system. Speed of sound and isentropic compressibilities have been compared with calculated values from free length theory (FLT), collision factor theory (M), Nomoto's relation (NR), Van Deal's ideal mixing relation (IMR) and Junjie's relation (JR). (C) 2003 Elsevier B.V. All rights reserved.