a given chlorinate cellulose is defined as the average number of substituted hydroxyl groups per anhydroglucose unit agu ds is determined from the chlorine content detected in elemental analysis in one or more embodiments the chlorinated polysaccharides or oligosaccharides obtained by the process of the invention have a degree of substitution ds of at least 0 5 there are 3 hydroxyl groups in the agu of cellulose and thus the theoretical maximum of the ds in chlorinated cellulose is 3 0 the first hydroxyl group in cellulose to be substituted by a chlorine atom will usually be the hydroxyl of the hydroxyl methylene group a specific ds of the chlorinated cellulose obtained by the process of the invention is 0 5 to 3 more specific is a ds of 0 8 to 3 suitable chlorinated cellulose obtained by the process of the instant invention may have for example a ds of 0 5 to 1 5 or from 0 8 to 1 5 with the process of the invention a ds in chlorinated cellulose of at least 1 0 can be easily achieved the chlorinating agent may be added in excess which means that more chlorinating agent may be added than required for the maximum ds non reacted chlorinating agents may be removed by usual means thionyl chloride may for example be removed by evaporation the chlorinating agent in particular thionyl chloride does not only effect the substitution of the hydroxyl group by a chlorine atom but leads also to a degradation of the poly or oligosaccharides in particular cellulose this degradation is caused by the fact that the chlorinating agent hydrolyzes the oxygen bridging between the repeating units of the main chain of the oligo or polysaccharide u03b2 1 4 glycosidic bonds thus the process.