Polyester having amino sulfonic acid moieties (TBES) was prepared by a liquid/solid biphase polycondensation of terephthaloyl chloride (TPC) and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES) in trimethyl phosphate (TMP) using triethylamine (TEA) as an acid acceptor. Blends of TBES with PVA and their metal complexes with Ni2+ and Co2+ ions were prepared. A strong interaction was observed between TBES and PVA. An electric conductivity of 10(-6) S cm(-1) was attained for the blend films containing about 5 wt % water. A coordination structure with two chelate rings is proposed for the metal complex with Ni2+ and Co2+ ions when the molar ratio of amino sulfonic acid groups in TBES to metal ions is larger than 2. Polymer blends complexed with Ni2+ or Co2+ ions result in semi-interpenetrating polymer networks from chelate formation.