Synthesis of ortho- and para-acryloylaminophenylarsonic acids (o-AAPHA and p-AAPHA) monomers and their homopolymers, useful as ion-exchange materials, are reported. Both the monomers and homopolymers are synthesized with > 90% yield. The structures of the new compounds are determined by NMR and FTIR spectroscopy. Molecular weights of the polymers are determined from light scattering measurements and found to be M-w = 38,759 g/mol for o-AA-PHA polymer and M-w = 31,347 g/mol for p-AAPHA polymer. Good thermal stability of the new compounds derived from their intra- or intermolecular hydrogen bondings suggests their applications as proton-exchange membrane at high temperatures. (c) 2006 Wiley Periodicals, Inc.