Isobaric vapor-liquid equilibrium (VLE) data of the systems acetic acid + N,N-dimethylformamide (DMF), acetic acid+dimethyl sulfoxide (DMSO), DMSO+water, water+acetic acid+DMF. and water+acetic acid + DMSO have been measured at 13.33 kPa by using an improved Rose equilibrium still, The association of acetic acid in vapor phase has been considered, and the nonideality of vapor phase was accounted for using the Hayden-O'Connell (HOC) method. The experimental binary data have been correlated by the NRTL, Wilson and van Laar models. The NRTL model parameters obtained from the binary data have been used to predict the ternary VLE data. The ternary predicted values obtained in this way agree well with the experimental values. (C) 2008 Elsevier B.V. All rights reserved.