Novel polyelectrolytes, o- and p-methacryloylaminophenylarsonic, (o-MAPHA and p-MAPHA) in their acid and salt forms were obtained from a promising aromatic monomer class with the functional group -AsO(OH)(2). These were characterised and some physico-chemical properties were determined. Reduced viscosity measurements at different pH showed a minimum suggesting that macromolecules have their minimum electrostatic repulsion conformation at pH it. The flocculation capacities of both polymers in their salt form were determined. Wastewater of the UAM-I University was used for the tests. Results are reported in terms of the residual turbidity variation versus polymer concentration and pH. Conformational changes of the polymer as a function of pH might be related to the flocculation of suspended solids in water-treatment operations. The novel polymers have advantages over other polymers, for instance 90% turbidity removal is achieved especially at low pH, (C) 2000 Elsevier Science Ltd. All rights reserved.