The biosorption potential of Padina sp. algae for the removal of strontium from aqueous solutions was studied. The effects of contact time, solution pH, initial metal concentration, and temperature on the strontium uptake by the algae were investigated. The pseudo-first-order, pseudo-second-order, and Weber and Morris kinetic models were applied to test the dynamic experimental data. The pseudo-second-order kinetic model provided the best correlation of the experimental data. The equilibrium experimental results were analyzed in terms of Langmuir, Freundlich, and Sips isotherms. Equilibrium data fitted very well to the Sips model. The maximum uptake estimated by using the Sips model was 330.38 mg/g at pH of 9.5 and temperature 45 degrees C. Using thermodynamic equilibrium coefficients obtained at different temperatures, various thermodynamic parameters, such as Delta G degrees, Delta H degrees, and Delta S degrees were calculated. The thermodynamics of the strontium ion-Padina sp. algaebiosorption system indicate an endothermic process at 288-318 K.