Bio-sorption of Pb2+ ion from wastewater with Chlorella was investigated in the batch mode. The influence of pH of the solution, biosorbents dose, concentration of ions and contact time on bio-sorption capacity of Pb2+ ions was studied. The studies revealed that Pb2+ ions uptake rate was rather slow, with 75% of the total amount occurring in the first 10min for Chlorella. The optimum pH for bio-sorption of Pb2+ ions was found to be about 5.5. The maximum percent removal was observed at biosorbent dose 1.0g/L; uptake capacity was decreased with increase in concentration of Pb2+. It also showed that factors affecting adsorption from strong to weak were biosorbents dose, pH, contact time and Pb2+ initial concentration; under the optimal conditions, the removal of Pb2+ was 94%.