A green and efficient process to synthesize monolithic porous inorganic materials with hierarchical structure has been presented. By using wood cellular structure as a template and supercritical CO2 as a solvent and carrier, the morphology and pore or channel systems of wood templates could be replicated faithfully. The total BET (Brunauer-Emmett-Teller) surface area of the resulting silica material can reach 469 m(2)/g using poplar as the template. It is found that different pore structure data can be obtained with different wood cellular structures as the template. Meanwhile, the pore structure data of the product can be adjusted by changing the experimental conditions of the supercritical CO2 during the impregnation process.