In this work an experimental determination of the vapor-liquid phase equilibria in the three-component system acetone(1) – n-hexane(2) – cyclohexane(3) was carried out at constant, atmospheric pressure. The experiment was carried out in two parts. In the first part, the vapor and liquid phase are separated on the Hunsmann apparatus, and in the second part the equilibrium compositions of the phases were determined by gas chromatography. The obtained results show that the two-component systems acetone(1) – n-hexane(2) and acetone(1) – cyclohexane(3) form azeotropes with a minimum boiling point temperature, and the n-hexane(2) – cyclohexane(3) system forms a mixture with regular behavior, so-called zeotrope mixture. When comparing experimental and literature data in isobaric phase diagrams, some deviations are observed. Thus, for the system acetone(1) – n-hexane(2) the mole fraction of n-hexane in the vapor phase is higher in the experiments performed here than in the literature, for the acetone(1) – cyclohexane(3) system the proportion of cyclohexane in the vapor phase is also higher in the experiments performed here, and for the n-hexane(2) – cyclohexane(3) system minor deviations are observed in the border regions of the composition range. Based on literature experimental data, i.e. isothermal vapor-liquid equilibria phase diagrams, the parameters of the Wilson, NRTL and UNIQUAC activity coefficient models were determined. The objective function value was applied to assess the deviations of the model from the literature data. Thus, the acetone(1) – n-hexane(2) two-component system was best described by the NRTL model, the acetone(1) – cyclohexane(3) system was best described by the Wilson model and the n-hexane(2) – cyclohexane(3) system was best described by the UNIQUAC model. Using the parameters determined in the two-component systems, the literature three-component system experimental data were successfully described. The same parameters were also used to describe the three-component system experimental data obtained in this work; the smallest deviations were found with the UNIQUAC model.