In　this　work,　a　new　procedure　for　the　selective　monohydrolysis　of　polyhedral　diesters　is　reported.　The　optimal　conditions　with　regard　to　the　catalytic　activity,　quantity　of　catalyst,　ultrasound　irradiation　power,　solvents　and　both　the　reaction　and　separation　temperatures　were　examined.　A　series　of　polyhedral　monoesters　were　obtained　in　high　yield　using　1-2　mol　%　of　p-toluene　sulphonic　acid　in　a　co-solvent　under　ultrasonic　irradiation.　This　work　not　only　leads　to　a　practical　synthetic　method　for　polyhedral　monoesters,　but　also　provides　a　new　approach　to　acid-catalyzed　selective　monohydrolysis.