Reverse micelle-type N,N-diarylammonium pyrosulfate (3鈥? mol %) efficiently catalyzes the hydrolysis of esters (up to 100 mmol scale) under organic solvent-free conditions. The present method is successfully applied to the hydrolysis of various esters without the decomposition of the base-sensitive moieties and without any loss of optical purity for 伪-heterosubstituted carboxylic acids.