Wood is an abundantly occurring hierarchically structured nanocomposite material. It consists of fibrils of diameter 10-20 nm, which are embedded into a lignin matrix. In these fibrils, cellulose nanofibrils of diameter 2-3 nm are surrounded by hemicelluloses. To make use of the complex hierarchical structure and the outstanding mechanical properties for synthetic ceramics, wood was used as a template for silica. This work is about the structure analysis of the wood templated silica with in-situ small-angle X-ray scattering (SAXS) during gas sorption and additionally gravimetric and volumetric sorption measurements using n-Pentane and N2 as sorptives. The main goal was to prove the accessibility of pores in these “wood ceramics” at the level of the original fibrils and nanofibrils of the wood. The thesis confirms earlier work that the structure of the wood templated ceramic is built up similar to the original wood structure with porous silica replacing the cell walls. The nanostructure consists of fibrils with slit-shaped mesopores of around 10 nm size. Within these fibrils, chiral micropores are placed instead of the cellulose nanofibrils. The results feature the existence of the pores but also attest their partial accessibility down to the nanofibrills. The results also show that this intricate structure is only reached for the sample preparation with a modification process including chemical cell wall modification, while other preparation methods lead to a much less developed nanostructure.