Poly-electrolyte N-vinyl 2-pyrrolidone-g-tartaric acid (PVP-g-TA) hydrogels with varying compositions were prepared in the form of rods from ternary mixtures of N-vinyl 2-pyrrolidone/tartaric acid/water. The effect of external stimuli, such as the solution pH, ionic strength, and temperature, on uranyl adsorption by these hydrogels was investigated. Uranyl adsorption capacities of the hydrogels were determined to be 53.2-72.2 (mg UO22+/g dry gel) at pH 1.8, and 35.3-60.7 (mg UO22+/g dry gel) at pH 3.8, depending on the amount of TA in the hydrogel. The adsorption studies have shown that the temperature and the ionic strength of the swelling solution also influence uranyl ion adsorption by PVP-g-TA hydrogels. (C) 2000 John Wiley & Sons, Inc.