A sulfonated polyarylenethioethersulfone polymer and copolymer. The sulfonated polyarylenethioethersulfone polymer and copolymer comprises the reaction product of an aromatic dihalo functionality sulfonated monomer, an aromatic dithiol monomer, and optionally an aromatic dihalo functionality monomer. The invention also relates to methods of making the sulfonated polyarylenethioethersulfone polymer and copolymer, and to membranes made from the sulfonated polyarylenethioethersulfone polymer and copolymer.