Pervaporation studied for the removal of the VOC traces from effluents is now used to dehydrate organic solutions and this paper is focused on an acetal called methylal. Different membranes and different operating conditions were investigated: pure quality or anhydrous qualities were obtained from technical or intermediate qualities. However, due to degradations and weak permeate flows, it is impossible to consider an industrial development using organic membranes. A ceramic membrane yields high permeate fluxes without degradation. (C) 2003 Elsevier Science B.V. All rights reserved.