The composition and structure of the solid and soluble products of birch wood delignification by H2O2 in the presence of TiO2 catalyst were studied. The efficient delignification of wood proceeds at 100 degrees C and atmospheric pressure. The obtained microcrystalline cellulose (yield 48.2% mass.), has crystallinity index 0.81 and contain 93.7% mass. cellulose, 5.5% mass. hemicelluloses and 0.5% mass. lignin. Soluble products of birch wood peroxide delignification are mainly presented by 4-O-methyl-glucuronoxylan (84% rel.), monosaccharides and they contain very few aromatic compounds.