However, there is no report on the carboxymethylation of hardwood kraft lignin. Currently, there is a surplus production of hardwood kraft lignin in the pulping process, which could be separated from black liquor (i.e. spent pulping liquor), and functionalized to produce value-added chemicals. The main novelty of this work was the production of a dispersant from hardwood kraft lignin via carboxymethylation for clay suspensions. The impact of carboxymethylation on the charge density of the product, which is known to be an important parameter for dispersants (and basically polyelectrolyte systems) [19], is discussed for the first time. In this context, the influence of reaction parameters on the preparation of carboxymethylated lignin from hardwood kraft lignin using sodium chloroacetate under alkali conditions were studied in order to obtain car- boxymethylated kraft lignin with a high charge density and solubility. The properties of carboxymethylated lignin were determined using NMR, TGA, FTIR, potentiometric titrator, charge density and elemental analyses. The dispersion perfor- mance of carboxymethylation lignin for a clay suspension was also studied using a particle dispersion analyzer (PDA).