The composite adsorbent prepared by mixing of polyacrylonitrile and clinoptilolite was used for investigating the adsorption behaviour of Ra-226 in column system. The effective parameters like initial activity concentration, pH of the solution, contact time and temperature for adsorption behaviour of Ra-226 were studied. Adsorption efficiency of Ra-226 on composite adsorbent from aqueous solution was determined to 98.73 +/- 0.59 % at pH 5.0 and 30 A degrees C in a short time. The isotherm models were studied to evaluated adsorption characteristics of Ra-226 onto composite adsorbent. The thermodynamic parameters were showing that the processes for Ra-226 were exothermic. Adsorption kinetics of the radium is also studied.