In this study, we demonstrated a high flux thin film nanofibrous composite (TFNC) membrane system based on polyacrylonitrile (PAN) electrospun scaffold coupled with a thin barrier layer of cross-linked polyvinyl alcohol (PVA). With carefully chosen structural parameters (i.e., a mid-layer PAN scaffold with porosity of about 85% and cross-linked PVA top coating with thickness of about 0.5 mu m), the demonstrated TFNC membrane system shall be very useful for ultrafiltration (UF) applications, exhibiting a very high flux (i.e., 12 times higher than that of conventional PAN UF membranes) and excellent rejection ratio (>99.5%) for separation of oil/water mixture (1500 ppm in water) over a long time period (tested up to 190 h) in a practical pressure range (up to 130 psig). (C) 2009 Elsevier B.V. All rights reserved.