Supported liquid membranes containing polyamine extractants have been stabilized with semi-permeable epoxy skin layers. Liquid-vapor interfacial polymerization reactions were employed to deposit the epoxy layers. Different monomers were explored to investigate their effect on the integrity, morphology, and chemical inertness of the resulting epoxy layers. Smooth, dense epoxy layers were formed on membranes containing undiluted 2-butyl-2-ethyl-1,5-pentanediamine, or 4-(aminomethyl)-1,8-octanediamine, by polymerization with 1,3-butadiene diepoxide vapor. Both amines yielded skin layers that are more resistant to strong acids than polyamide skin layers. The 4-(aminomethyl)-1,8-octanediamine yielded a crosslinked epoxy skin layer that could withstand exposure to acetic acid. The resulting stabilized membranes transported acetic acid at a flux of ca. 100 mu mol/m(2) s.