This study describes the lithium (I) uptake behavior of Dunaliella salina alga for a potential functional nutritional supplement. For this purpose, cultivation of the isolated D. salina strain in a lithium (I)-free medium was followed by the harvesting and drying of the cells. The characterization studies of the alga revealed that D. salina has a high surface negativity, which has a direct positive effect on its ability to capture lithium (I) ions. Critical parameters such as pH and initial lithium (I) concentration, which directly affect the lithium (I) uptake of the cells, were optimized. The maximum lithium (I) uptake capacity of D. salina was determined as 4.003 mg lithium (I)/g dry biomass (576.7 mu mol/g) at an initial lithium (I) concentration of 20.0 mg/L and pH of 9.0. Lithium (I) uptake by the alga rapidly reached equilibrium for all cases examined. Experimental equilibrium data were found to be compatible with both Langmuir and Freundlich models under the experimental conditions studied. It can be said that D. salina with its efficient lithium (I) ion uptake holds great promise in the nutrition, pharmaceutical and seawater feeding industries.