Isobaric　vapor-liquid　equilibrium(VLE)　data　for　acetic　acid　+　sec-butyl　acetate　and　water　+　acetic　acid　+　sec-butyl　acetate　systems　were　determined　at　101.3　kPa　using　a　modified　Rose　type.　The　nonideality　of　the　vapor　phase　caused　by　the　association　of　the　acetic　acid　was　corrected　by　the　chemical　theory　and　Hayden-O＇Connell　method.　Thermodynamic　consistency　was　tested　for　the　binary　VLE　data.　The　experimental　data　were　correlated　successfully　with　the　Non-Random　Two　Liquids　(NRTL)　model.　The　Root　Mean　Square　Deviation　(RMSD)　of　the　ternary　system　was　0.0038.　The　saturation　vapor　pressure　of　sec-butyl　acetate　at　329　to　385　K　was　measured　by　means　of　two　connected　equilibrium　cells.　The　vapor　pressures　of　water　and　sec-butyl　acetate　were　correlated　with　the　Antoine　equation.　The　binary　interaction　parameters　and　the　ternary　VLE　data　were　obtained　from　this　work.