A composition comprising: a) 5 to 65 wt % of curable compound comprising one ethylenically unsaturated group and at least one anionic group; b) 2.5 to 70 wt % of crosslinking agent comprising at least two acrylic groups; c) a tertiary amine; and d) 0 to 45 wt % of inert solvent; wherein the molar ratio of component c) to a) is at least 0.7. Also described are a process for making composite membranes and the resultant membranes.