The removal of Cr6+ ions with Ulothrix zonata, a species of green algae, was studied at a fixed temperature and mixing rate. Initial metal ion concentration, initial pH, biomass concentration and the effect of contact time were investigated and their suitability to adsorption isotherms was examined. It was observed that the results were in conformity with the Freundlich adsorption isotherm. The highest uptake was achieved at 30 min. and pH=1.0. The removal ratio of Cr6+ respectively founded 96%, 47%, 44%, 34%, 30% at 5, 25, 50, 100, 150 mg/L metal concentration.