The performance of Friedel's salt (FS: 3CaO·Al₂O₃·CaCl₂·10H₂O), a layered double hydroxide (LDHs), as an adsorbent for cobalt (Co²⁺) removal from its solution was investigated. Friedel's salt was synthesized by reaction of tricalcium aluminate with calcium chloride. The stability of FS at different pHs was studied. Also, the adsorption behaviors of Friedel's salt for cobalt (Co²⁺) from its solution at different concentrations and pH=4 at room temperature and 50ºC was examined. The results showed that, high stability for FS in neutral medium (pH=6) than in basic (pH=8) and acidic medium (pH=4). In addition, the results indicated that the adsorbent FS had an outstanding ability for Co(II) adsorption. The maximum adsorption capacity of the FS for Co (II) removal can reach to 1903.44 mg/g. Furthermore, the increase in the temperature (50º C) effect positively on the rate of adsorption.