Abstract: The invention relates to a method for separating hemicelluloses from a biomass containing hemicelluloses. Said method comprises the following steps: a) the hemicelluloses are extracted from the biomass containing hemicelluloses by means of treatment with a complex compound in an aqueous solution, forming a soluble hemicellulose complex, and b) the complexed hemicelluloses are separated from the biomass. The inventive method is especially suitable for producing high-quality chemical conversion pulp from raw cellulose. Not only does the inventive method enable the obtained products to have a high degree of purity, but it is also extremely economical and causes few emissions. The inventive method is also characterised in that polymer hemicelluloses in a pure form can be obtained as by-products.