The retention of Pb (II) from aqueous solution by pure (PB) biomass and thioglycolic acid (TGA) modified biomass (MB) of Nipah palm (Nypa fruticans Wurmb) petiole was studied using batch sorption technique. The equilibrium retention capacity of Pb (II) was determined from the Langmuir equation and found to be 15.06 mg g-1 and 17.60 mg g-1 for pure and modified biomass, indicating a small difference in Pb(II) retention after treatment with TGA. The data showed that chemisorption process could be the rate-limiting step in the retention mechanism. Studies on the retention of Pb (II) by Nipah palm petiole biomass are important because it may contribute in aiding the innovative removal and recovery of metal ions from contaminated industrial effluents