The kinetics and mechanism of the disproportionation of MnO4-via [CMC-MnVIO42-] intermediate complex formation during the oxidation of carboxymethyl-cellulose (CMC) polysaccharide have been investigated spectrophotometrically at pH greater than or equal to 12 and various temperatures (15-35 degreesC). The rate law was suggested as rate = k(obs)[MnO4-]. Kinetic and spectrophotometric measurements revealed the base-catalyzed formation of manganate(VI) transient species. A mechanism was postulated consistent with the experimental data.