In the last decades mechanochemistry has advanced quickly and has been acknowledged as one of the top ten emerging technologies in chemistry. One field of mechanochemistry is mechanocatalysis where a suitable catalyst for a reaction is added to the reactants. For these reactions many different reactor types such as vibration mills, mortar mills and rotary mills can be used. In terms of green chemistry, this approach has the advantage that they are usually solventfree while there are also approaches with solvents, the so-called liquid assisted grinding (LAG). Mechanochemistry is probably most known for processing inorganic materials such as alloys and intermetallic phases. Typical examples are the synthesis of oxides, nitrides and halides where long reaction times up to several days are required. Besides the synthesis of inorganic materials there are also rising numbers of mechanocatalytic organic synthesis e.g. Knoevenagel-condensations and polymerizations of insoluble polymers whereby the synthesis of thermoplastics is not favored due to the released heat during the process. In some cases, this typical solvent-free approach enables activation only due to mechanical forces, e.g. breaking the rigid structure of cellulose and lignocellulosic structures , thereby rendering this method highly attractive for the processing of lignocellulosic residues as reported previously. In contrast to the polymerization of specific polymers the depolymerization of lignocellulosic feedstocks and cellulose as readily available renewable feedstock is of great interest. Cellulose and lignocellulosic feedstocks are commonly insoluble and therefore difficult to process. It is known that by mechanocatalytic processing of cellulosic biomass with a strong acid a soluble product mixture consisting of glycans (glucans and xylans), as well as partially depolymerized lignin is obtained. This is an advantage compared to classic wood saccharification since the more valuable glycans instead of monomeric sugars can be formed. Furthermore, it was shown that glucose itself can oligomerize during mechanocatalysis, which means that complete depolymerization to monomeric sugars is not possible (Figure ). Figure : Mechanocatalytic partial depolymerization of cellulose to oligomeric glycans without formation of monomeric sugars.