This work includes the description of remarkable progresses towards the exploitation of raw biomass for the synthesis of sustainable and functional carbon materials. It highlights the high potential of the hydrothermal method as a means of conversion of waste or cheap biomass into value added products in complete agreement with the “Biorefinery Concept”. Furthermore it represents an important contribution to the overall HTC research field, since it proposes a new reaction mechanism for cellulose HTC conversion and it presents a detailed investigation of HTC carbon pyrolysis, which can be used as a further post-synthesis functionalisation step. It also demonstrates the high suitability of HTC carbons as precursors for the synthesis of highly microporous ACs having several foreseeable applications (e.g. CO2 capture, high pressure CH4 storage and supercapacitors) and representing a carbon neutral/negative alternative to the fossil fuels derived carbon materials.