The aim of this work was to study the effect of the degree of substitution (DS) and the purity of sodium carboxymethyl cellulose (CMCNa) prepared from Tunisian vine stem on the absorption and retention of water. Vine stem was first delignified using souda-anthraquione, then bleached and finally chemically modified, in order to synthesize different CMCNa derivatives. The carboxymethylation reaction was carried out in presence of NaOH (40 %) and monochloroacetic acid (ClCH2COOH), in n-butanol as a reaction solvent. The obtained CMCNa derivatives were characterized using different tools such as the DS, Fourier transforms IR techniques, CP-MAS 13C-NMR, the exchange capacity as well as the determination of modification reaction yield. The performance of the prepared derivatives in term of absorption capacities and retention capacities was established. The performance of CMCNa derivatives was compared with that achieved by commercial counterparts and it was concluded that the prepared ones exerted higher efficiency.