Studies on the extraction behavior and immobilization of cadmium by greener reagents have important bearings in today’s science. No-carrier-added (NCA), 109Cd radionuclide is a potential candidate towards radiopharmaceutical studies for both in vivo and in vitro applications and is also used in industrial and environmental studies. Herein, we have studied the adsorption and desorption characteristics of cadmium in both NCA and bulk concentrations into calcium alginate using radiochemical method. Various isotherms like Langmuir, Freundlich, Temkin and Dubinin–Radushkevich have been studied and compared to match the adsorption phenomenon. A spontaneous endothermic physisorption process is expected from thermodynamic parameters. © 2017, Akadémiai Kiadó, Budapest, Hungary.