The reactions with cocoa shells were carried out in the same way as those of wheat straw. For cocoa shells a 7-8 % increase of the soluble fraction could be obtained (Figure ). Compared to wheat straw this increase seems quite small. This small increase can be attributed to the high phenolic content with 32.2 % as well as the low carbohydrate content with 11.4 % where the molecular structure is more rigid. This is consistent with the expectation of a more hindered reaction for this natural raw material. Furthermore, condensation reactions of phenolic molecules (tannins) and between phenolic molecules and other macromolecules (proteins, polysaccharides) may counteract depolymerization. In sum depolymerization of cocoa shells without pretreatment has a low efficiency.