The invention refers to a method for the production of cellulose sulfate which is completely water-soluble and has an adjustable solution viscosity in aqueous solution, which qualifies the produced sodium cellulose sulfate (SCS) as auxiliary material with ideal biological compatibility for biological and medical applications, in particular it is suitable for the encapsulation and immobilization of biological objects, e.g. tissue, cells, microorganisms, enzymes or viruses in microcapsule.