Characterization of kepok banana (Musa balbisiana Colla) bark powder to determine the chemical composition and functional groups which play a role in the absorption of Pb(II) and Cd(II) metal ions in aqueous solution, has been performed. The functional groups owned based on FTIR are hydroxy group at wave numbers of 3422.77 cm-1, alkanes at wave numbers of 2919.27 cm-1, and carbonyl at wave numbers of 1636.50 cm-1. To determine the absorption capacity of Pb(II) and Cd(II) metal ions by banana bark powder,it was studied the effect of pH, particle size, weight of biomass and contact time. The results showed that the maximum capacity (Qm) for Pb(II) metal ion is 10.9215 mg/g and Cd(II) metal ion is 2.8275 mg/g, obtained at pH 4, contact time of 90 minutes and mass of 0.1g for both metal ions,whilethe particle size is 180 μm for Pb(II) metal ion and 150 μm for Cd(II) metal ion. Theinitial concentrations for Pb(II) and Cd(II) metal ions are 50 mg/L and 15 mg/L, respectively. Based on the data obtained, it can be concluded that kepok banana bark powder can be used as biosorbent for the absorption of metal ions in aqueous solution.