Industrial development, population growth, and application of new technologies have causedcontamination of soil and water resourcesby heavy metals. Industrial production of metal alloys, plastics, paints, and resi mining activities;vehicular traffic; and application of chemical fertilizers and biosolids are the main sources ofheavy metals in contaminated water bodies. Adsorption is an effective and economic process for removal of heavy metals from polluted waters. In this study, zeolites and sepiolite clay minerals and alginate biopolymerwere used for adsorptive removal of Pb from aqueous solutions. Several hybrid adsorbent with different ratios of clay to alginate (1:2, 1:4 and 1:8) were also prepared and their abilitiesto adsorb Pb were compared with those of the clays and alginate. The sorption experiments were carried out in different Pb concentrations (25 to 2000 mg L -1 ) and temperatures(15, 25, 35 and 45C?) to determine the isothermal and thermodynamic constants for Pb sorption. The results showed that the Langmuir and Freundlichmodels described Pb sorption on all sorbents very well. Based on the Langmuir model, alginate showed the highest and clays showed the lowest sorption capacities for Pb and the hybridsorbents were intermediate in Pb sorption. The capacitiesof all sorbents for Pb retention increasedwith increasing temperature from 15 to 45 ? C. Negative values were calculated for the Gi free energychanges, indicating thatPb sorption on the sorbents was spontaneous.Positive values were calculated for the enthalpy change, suggesting that Pb sorption reaction was endothermic in nature. Positive values were also obtained for the entropy changes, which indicates the increased randomness at the solid/solution interface with some structural changes in the sorbate and sorbents.ased on the values of the obtained thermodynamic parameters,it can be concluded that chemisorptionwas the main mechanism for Pb sorption by the studied sorbents. At all temperatures, by increasing the proportion of zeolite in clay-alginate hybrids,an increasingtrend in Pb sorption was observed. But in the case of sepiolite-alginatehybrids, no significant differences in Pb sorption were detected among thehybrids.