Isobaric vapor liquid equibrium (VLE) data for (acetic acid + cyclohexane) and (cyclohexane + acetylacetone) were determined at a pressure of 101 3 kPa and those. for (acetic acid + acetylacetone) at a pressure of 60 0 kPa A minimum boiling azeotrope was found for (acetic acid + cyclohexane). The nonideality oh the vapor phase of (acetic acid + acetylacetone) and (acetic acid + cyclohexane) was investigated by using the Hayden-O'Connell equation Thermodynamic consistency was tested for all of the VLE data The experimental data were correlated satisfactorily by the Wilson. NRTL, and UNIQUAC models Correlation results were in good agreement with experimental data