Banana (Musa paradisiaca) Stalk (BS), an agricultural waste, modified by graft copolymerization reaction might be the basis of a new approach to remove the metal pollutants from water. The treatment process involves graft copolymerization of acrylamide onto BS using ferrous ammonium sulphate/H2O2 redox initiator system followed by functionalization of carboxylate group (PGBS-COOH). In this paper, the efficiency of the PGBS-COOH in the removal of Co(II) from aqueous solutions has been investigated using batch experiments. The influence of different experimental parameters such as pH, contact time, initial concentration of Co(II), adsorbent dose and temperature on the adsorption process has been studied. The maximum adsorption capacity is observed at the pH range 6.5-8.0. Maximum removals of 99.7 and 97.2% are observed at Co(II) concentration of 25.0 and 50.0 mg/L, respectively. A kinetic model based on empirical relationship has been derived to predict the percentage Co(II) removal at any time for known amount of sorbent and initial Co(II) concentration. The surface mass-transfer coefficient as a function of temperature has been determined. Kinetic parameters are also evaluated. The Langmuir isotherm model fitted the experimental equilibrium data. The PGBS-COOH had adsorption capacities for Co(II) from 166.66 mg/g at 30 degrees C to 181.46 mg/g at 60 degrees C. Graft copolymerization of BS-an agricultural waste which is found in abundance and has otherwise no significant use and results in a low cost-value-added product which can benefit industry.