We report the preparation and characterization of phosphonium-based bicarbonate anion exchange random copolymers, poly(styrene-random-trimethylvinylbenzyl phosphonium bicarbonate) (poly(S-r-TMVBP-HCO3)). Compared to the chloride anion (Cl-) exchange membranes, these HCO3- exchange membranes exhibit similar hydration levels and only slightly lower ionic conductivities at similar ionic compositions. Other experiments reveal that the HCO3- exchange membranes are thermally stable (up to 110 degrees C) and chemically stable under relatively low alkaline conditions. Additionally, a detailed chemical degradation mechanism for these membranes under strong alkaline conditions is presented. (C) 2013 Elsevier B.V. All rights reserved.