Abstract: Bipolar membranes are disclosed which exhibit high permselectivity, good mechanical strength, ability to operate at high current density, low potential drop and long-term stability. Essential to the production of bipolar membranes with these properties is the construction of the interface layer, which includes a matrix material containing quaternary and non-quaternary amine groups and having dispersed therein a cation exchange resin. A number of additional important characteristics are disclosed directed to the construction of the anion and cation layers of the bipolar membranes. A preferred method for forming bipolar membranes by casting layers on top of one another is also disclosed.