Cobalt is a metal commonly used in alloys, metal-mechanic and battery industries. An alternative and selective methodology for the removal of cobalt from the environment has always been wanted due to its negative impact on ecology and public health. Spent green tea (GT) and decaffeinated tea (DGT) leaves were used as potential adsorbents of Cobalt (II) ions from aqueous solutions. Equilibrium parameters such as pH, mass of adsorbent and initial concentration of cobalt metal ions were studied to optimize the adsorption in discontinuous experiments at room temperature. Experimental data indicates that adsorption of cobalt (II) is maximized at pH 6 using 150 mg of both adsorbents. Langmuir and Freundlich isotherm models were fitted to the experimental results, indicating maximum adsorption capacities of 31.59 and 32.43 mg/g for GT and DGT, respectively. SEM images and EDAX analyses indicate the presence of pockets and pores and demonstrate the presence of the cobalt ions on the surface of both adsorbents. These results suggest that GT and DGT have potential as eco-friendly adsorbents of divalent cobalt ions from solutions.