The effects of temperature, pH and ionic strength on adsorption of Cd(II) and Pb(II) onto carboxymethylated lignin from sugar cane bagasse have been studied. Adsorption equilibrium data obtained using the batch technique were fitted to the Langmuir model. A factorial design showed that the most important variables are temperature and ionic strength for the Pb(II) adsorption in single and binary system respectively. For both metals, maximum binding capacity decreased with the ionic strength increase. Increasing pH the Pb(II) adsorption is enhanced. Carboxymethylated lignin adsorbed Pb(II) selectively at pH 6.0, 30 degrees C and 0.1 mol dm(-3) of ionic strength.