The adsorption behavior of Ni(II) onto bentonite was studied as a function of temperature under optimized conditions of shaking time, amount of adsorbent, pH, and concentration of the adsorbate. Thermodynamic parameters such as DeltaH(degrees), DeltaS(degrees), and DeltaG(degrees) were calculated from the slope and intercept of the linear plot of 1gK(D) against 1/T. Analysis of adsorption results obtained at T = (298, 303, 313, and 323) K showed that the adsorption pattern on bentonite followed the Langmuir, Freundlich, and D-R isotherms. A flame atomic absorption spectrophotometer was used for measuring the concentration of Ni(II). (C) 2003 Elsevier Ltd. All rights reserved.