Decontamination of synthetic Ni(II), Cd(II) and Pb(II) Solutions using poplar sawdust Was investigated. Batch sorption studies have been carried Out to determine the effect of contact time, temperature and initial Concentration of heavy metal ions (HMI) on adsorption. Equilibrium time was found to be around 60 min. Pseudo-first-order, pseudo-second-order and intraparticle diffusion models were used to fit the experimental data. Adsorption isotherms showed that HMI adsorption on sawdust deviated from the Freundlich and Langmuir equations. The Freundlich and Langmuir constants were calculated at different temperatures (25, 45 and 60 degrees C). Thermodynamic parameters, Such as free energy, entropy and enthalpy changes for the adsorption of heavy metal ions have been also Computed and discussed. In addition, the adsorption competition of Ni(II), Cd(II) and Pb(II) ions was determined from the A% values obtained from double and triple mixtures of these ions. Ion exchange is probably one of the major adsorption mechanisms for binding divalent metal ions to poplar sawdust.