The　effects　of　water　on　steam　rectification,　i.e.,　multi-stage　saturated　steam　distillation,　were　investigated　in　a　packed　column.　N-octane-p-xylene　and　1,3,5-trimethylbenzene-1,2,4-trimethylbenzene　were　used　as　test　systems.　Both　binary　systems　are　nearly　ideal　systems　and　insoluble　in　water,　thus　the　effects　of　water　in　steam　rectification　can　be　clearly　and　definitely　revealed.　Such　unpolar　organic　liquid　is　named　as　＂oil＂　The　water/oil　at　column　top　can　be　separated　and　refluxed　at　different　ratio.　Compared　with　conventional　rectification,　there　are　some　peculiar　phenomena　in　steam　rectification.　Water　greatly　enhances　the　flooding　vapor　velocity　of　the　rectification,　in　addition,　water　plays　a　predominant　role　in　pressure　drop　of　the　packed　bed　near　flooding　point.　It　is　clear　that　liquid　water　in　the　packed　bed　can　promote　mass　transfer　of　steam　rectification,　especially　for　materials　with　higher　viscosity.　In　a　word,　steam　rectification　can　be　operated　at　low　temperature　with　good　mass　transfer.　©　2011　The　Institution　of　Chemical　Engineers.