The Hydrothermal Carbonization is one possibility to concentrate energy of wet biomass in so called biochar. To design technical HTC-reactors in a rational way, the reaction kinetics of the four main components of biomass - Carbohydrates, lignin, fats / oils and proteins - should be known. In a previous work, the HTC of cellulose was published. Furthermore, the kinetic of change of the biochar plays an important role. The focus of this work is on the investigation of the HTC of lignin which is a highly complex, chaotic macromolecule. Therefore, one of its building units – vanillin – is also investigated as a model component.