Oscillatoria anguistissima rapidly adsorbs Cu2+ from aqueous solution, The adsorption of Cu2+ followed Freundlich Isotherm, and the amount of Cu2+ removed from solution increased with increasing Cu2+ concentration. The adsorption is pH dependent, and maximum Cu2+ removal occurs at pH 5. Of the various pretreatments, HCl treatment of the biomass increased the capacity for Cu2+ removal. Presence of Mg2+ and Ca2+ resulted in decline in the Cu2+ adsorption capacity of Oscillatoria cells, This species could also effectively remove Cu2+ from mine water containing 68.4 mu g/ml of Cu2+ at pH 3.45.