Pervaporation is a good option to enhance conversion in reversible esterification reactions, generating water as a by product. In present work, polyvinyl alcohol-polyether sulfone (PVA-PES) composite hydrophilic membrane was used for pervaporation-assisted esterification of lactic acid with n-butanol. Pervaporation reactor is an esterification reactor combined with pervaporation membrane module. Experimental work of esterification of lactic acid with n-butanol coupled with pervaporation was carried out. Effect of various parameters, such as, initial mole ratio of n-butanol over lactic acid, the ratio of the effective membrane area over the volume of reacting mixture, process temperature and catalyst concentration on the performance of pervaporation reactor were discussed. The following optimum conditions were obtained: temperature = 90 degrees C, catalyst concentration = 0.422 kmol/m(3), initial molar reactant ratio (n-butanol / lactic acid) = 1.4, ratio of effective membrane area to the reaction volume = 15.19 m(2)/m(3). The presented data can be extended for study and design of pervaporation reactor for similar kind of reactions.