Polyelectrolyte complexes (PECs) constitute a large family of multi-component polymeric materials with rich functionalities. PEC membranes (PECMs) have already been utilized in pervaporation, nanofiltration and fuel cells. In literature, these PECMs were prepared in different methods so that they have the desired structures suitable for targeted applications. For instance, there have been two-ply PECMs, blend PECMs, multilayered PECMs, and homogeneous PECMs that have been utilized for different applications. A systematic retrospect on PECMs will not only propel present research but also stimulate new application potentials of PECMs. This review article focuses on the physical background, preparation and application aspects of PECMs in pervaporation, nanofiltration and fuel cells. (C) 2011 Elsevier B.V. All rights reserved.