A green one-step catalytic process of obtaining microcrystalline cellulose (MCC) from wood in the medium “acetic acid–hydrogen peroxide–water” in the presence 2% wt. sulfuric acid catalyst is described. The influence of wood nature and conditions of the process on the yield, composition and structure of obtained samples of MCC was investigated. For hardwood (aspen wood and birch wood) the minimal content of residual lignin (<1% wt.) was achieved under the following conditions: temperature 130 °C, the concentration of H2O2 4% wt., the concentration of CH3COOH ∼ 26% wt., liquor ratio of 10 and the process time of 3 h. At these conditions, the degree of delignification of softwood (spruce wood and larch wood) is lower than for hardwood. According to X-ray and FTIR data, the structure of MCC samples obtained from wood is close to that of MCC Avicel and MCC from cotton linter.