The Oscillatoria sp. H1 (Cyanobacteria) isolated from Mogan Lake was researched for the removal of chromium (VI) ions from aqueous solutions and were used free (dry biomass), immobilized (in Ca-alginate) live and immobilized heat-inactivated biomass as biosorbents. Particularly, the effects of physico-chemical parameters like pH, the temperature change, initial concentration, biosorption time and biosorbent dosages on the biosorption of Cr (VI) ions were investigated. The biosorption of Cr (VI) ions for all biosorbents was determined as a highest value at pH 6.0. The temperatures which changed between 20 and 40 degrees C did not affect the biosorption capacity.