The　diode　behavior　of　ferroelectric　materials　was　shown　to　be　enhanced　using　aqueous　solution　treatment　of　their　surface.　The　electric　current　increased　for　both　BaTiO3　and　BiFeO3　nano-films　after　being　treated　with　aqueous　solution　as　compared　with　their　as-grown　films.　The　hydroxyl　groups　were　confirmed　to　be　successfully　bonded　on　the　surface,　which　increased　the　concentration　of　oxygen　vacancies　near　the　film　surface.　The　rectifying　diode　effect　can　be　associated　with　the　polarization　direction　and　the　movement　and　redistribution　of　oxygen　vacancies　within　the　ferroelectric　thin　films.　Further　the　enhanced　diode　effect　for　the　hydroxylated　film　was　attributed　to　the　increased　oxygen　vacancies　near　the　top　electrode/film　interface.　The　reported　finding　helps　us　understand　the　role　of　water　as　the　most　common　polar　molecule　in　the　atmosphere　on　the　ferroelectric　materials　that　exist　in　many　industrial　devices.　This　will　provide　a　low-cost　strategy　for　improving　the　performance　of　resistive　memory.