Non-porous hollow fibers are used as structured packing in the distillation of isopropanol-water solutions. The fibers used are non-selective, and offer little resistance to mass transfer. Liquid flows through the lumens of the fibers, and vapor flows countercurrently outside the fibers. The number of transfer units (NTUs) obtained is consistent with earlier correlations for membrane module mass transfer. The advantage of this form of structured packing is that liquid and vapor fluxes are not affected by two-phase fluid mechanics, so that the column can operate above the normal flooding limits, and below the normal loading limits. This offers the possibility of distillation with improved energy efficiency. (C) 2003 Elsevier Science B.V. All rights reserved.