Poly(acrylic acid-co-acrylamide) (PAAAM) hydrogels have been prepared from partly neutralized acrylic acid (AA) and acrylamide (AM) by solution polymerization, and their absorbency and adsorption in both CuCl2 and FeCl3 solutions have been investigated. PAAAM hydrogels and their complexes with Cu2+ or Fe3+ have been characterized by FTIR. The absorbency of PAAAM in both CuCl2 and FeCl3 solutions increases initially and then decreases as the absorbing time increases. The adsorption of PAAAM in both CuCl2 and FeCl3 solutions can be described by the pseudo-second order chemisorption kinetics pro osed by Ho and McKay, and the equilibrium uptake of Cu2+ on PAAAM can well be fit with the Langmuir adsorption isotherm. However, the equilibrium uptake of Fe3+ on PAAAM increases as the initial Fe3+ concentration increases for Fe3+ concentration smaller than 5.625 x 10(-3) mol/L, and then decreases with Fe3+ concentration. The largest uptakes for Cu2+ and Fe3+ are 247 and 173 mg/g, respectively. The results also show that the uptake Of Cu2+ and Fe3+ on PAAAM increases remarkably when pH of the solution is changed from 2.3 to 4.2 and from 1.0 and 2.1, respectively. (C) 2007 Wiley Periodicals, Inc.