Structural changes of wood and its components have been studied after shear deformation under high pressure (SDHP) at up to 6 GPa. Cellulose amorphization and chain depolymerization was observed. Approximately 30% of microcrystalline cellulose was soluble in water after a 360-degree twist of the Bridgman anvils. The water-insoluble part was recrystallized into cellulose II lattice. Repeated treatment applied to the nondissolved part of the sample, the so-called cascade experiment, permits the dissolving of about 30% of the residual nondissolved material once again. Extraction with water, followed by 10% sodium hydroxide, allows almost complete dissolving of microcrystalline cellulose (98%). Water-soluble saccharides were studied by HPLC and C-13 NMR. It was found that destruction of the wood lignin network needs more severe treatment conditions than cellulose destruction does. Lignin domains in wood act as "grinding stones" during cellulose destruction. Long-living lignin free radicals have been detected with EPR after SDHP. C-13 NMR CP/MAS spin diffusion studies showed that SDHP leads to separation of wood components into different biopolymer domains, which turns the system toward thermodynamic equilibrium. SDHP does not permit achievement of initial compulsary compatibility of components in native wood. SDHP technique appears as a promising method for wood delignification and carbohydrate saccharification in the solid state without using harmful chemical reagents or solvents, which is important for technological safety and ecology.