It has been found that by using suitable combinations of chemical and mechanical degradation of fibrous cellulose materials and by drying and fractionating them, it is possible to prepare cellulose powders having different physical and chemical properties such as degree of polymerization, crystallinity index, crystallite size, heat of wetting, specific surface area, and others. This opens futher new possibilities to use these materials in various industrial applications. Of course, chemical modification of these powders (i.e., introduction of carboxylic, sulphonic or acetyl groups) considerably extends the possibility. -- AATA