The adsorption of papain on the dye affinity membranes, the Cibacron Blue F3GA as a ligand, and the chitosan-coated nylon membrane as a base, under batch equilibrium experimental conditions at 277, 298, and 310K was investigated. The experimental data were analyzed using two adsorption kinetic models: the pseudo-first-order and the pseudo-second-order. The pseudo-second-order kinetic model provided the better correlation to the experimental results. Studies showed that the adsorption of papain on dye affinity membranes could be described by the Freundlich isotherm. The thermodynamic constants of adsorption phenomena: Delta G degrees, Delta H degrees, and Delta S degrees were found as -12.58 kJ/mol (at 298 K), 17.81 kJ/mol, and 0.101 kJ/(mol K), respectively. The result shows that the adsorption of papain on the dye affinity membranes was endothermic and spontaneous. (c) 2007 Elsevier B.V. All rights reserved.