A Cd(II) imprinted mercapto-functionalized silica gel sorbent was synthesized via a surface imprinting technique for selective adsorbent of Cd(II) ion in aqueous. The adsorbent was characterized using infrared (IR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive x-ray (EDX) spectroscopy. The adsorbent of Cd(II) ion-imprinted ionic polymer (Cd(II)-IIP) has higher capacity and selectivity than the non imprinted polymer (NIP) adsorbent. Adsorption capacity of Cd(II)-IIP and NIP are 83.89 and 35.91 mg g(-1) respectively. The largest selectivity coefficients (alpha) of the Cd(II)-IIP sorbent for Cd(II) in the presence of Ni(II), Cu(II) and Zn(II) are 99.798, 93.045, and 86.617 respectively. The relative selective factor (alpha(r)) values of Cd(II)/Ni(II), Cd(II)/Cu(II) and Cd(II)/Zn(II) are 41.687, 65.617 and 66.937, which are greater than 1. The prepared imprinted ionic sorbents exhibit high reusability. The results suggest that these Cd(II)-IIP can be used several times without considerable loss of adsorption capacity. (c) 2009 Elsevier B.V. All rights reserved.