The multicomponent solubility of mixed liquid species in crosslinked poly(dimethyl siloxane) (PDMS) films was determined with a gravimetric method at 35 degrees C. The series of binary liquid mixtures considered is formed by one non volatile and one volatile component: the latter can be acetone, n-pentane or tert-butanol. Acetone and n-pentane were mixed, separately, with vegetable oil and oleic acid; acetone has been also mixed with squalene and n-pentane with n-eicosane, while tert-butanol was mixed with poly (ethylene glycol) (PEG) 400. In most cases, the more volatile component is also the more soluble in PDMS, and its presence in the mixture enhances the solubility in the polymer of the less volatile one with respect to pure component value, of a factor as high as 25. In particular, a maximum in the solubility of the less volatile component is observed for intermediate fractions of the more volatile one in the liquid mixture. The present findings were applied to the simulation of a membrane-based deacidification process of vegetable oil containing variable amounts of acid, in the presence of a volatile solvent (acetone, n-pentane) and the optimal composition range was identified to maximize solubility and solubility-based separation factor. (C) 2015 Elsevier B.V. All rights reserved.