Oxidation process for producing polycarboxylates from polysaccharides

The process of producing polycarboxylic acids or salts thereof comprising introducing a polysaccharide to nitrogen dioxide and dinitrogen tetroxide at a charging temperature in the range from the boiling point of nitrogen dioxide under a particular pressure to a temperature which is 50.degree. C. higher than said boiling point wherein the introduction of nitrogen dioxide and dinitrogen tetroxide is terminated when 60% to 85% of the required degree of conversion of said primary alcohol groups into carboxyl groups is reached and then oxidizing the primary alcohol groups of said polysaccharide at a temperature which is at least about 10.degree. C. above said charging temperature to convert said alcohol groups into carboxyl groups, and optionally, at least partially neutralizing the carboxylic acid groups formed.