Vapor-permeation-(VP) aided esterification of oleic acid with ethanol was investigated at the boiling temperatures of the reaction mixtures under atmospheric pressure using a laboratory module of polyimide hollow fiber. The combined process provided almost complete conversion in a short reaction time with a decrease in the initial molar ratio of ethanol to oleic acid. This is attributed mainly to more rapid elimination of water as the result of the higher enrichment of water component in the vapor phase. The membrane module worked stably for the long period, because it was in contact with only the volatile components, namely water and ethanol. The VP-aided esterification was well simulated using the experimental data of both the reaction temperature and the permeation flux for each experimental run.