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Forestry lignocellulosic biomass is a major renewable energy sources in the world. Carbon generated by Nature through photosynthesis process, could potentially be considered as a neutral energy carrier in term of the greenhouse gas emissions, if it is produced is assured through sustainable plantations use. Cellulose is the main component of biomass (50% in weight on a dry basis in average) and its conversion into high density energy carrier like charcoal, gives relatively low charcoal yield (< 15%). The development of more efficient conversion technologies in terms of yield of charcoal is of primary importance for both developing countries than for industrialized countries. In the first case, the firewood and charcoal are the main sources of energy to the people. In the second case, the development of sustainable energy sources from biomass for biorefinery applications are of primary importance. The work aims to present our first results of the cellulose pyrolysis kinetic study at Elevated Pressure by specific Thermogravimetric Analysis (TGA-EP). The aims are (i) to assess the influence of pressure on the pyrolysis reaction kinetics and, (ii) to determine charcoal yield benefit. After a brief presentation of the TGA-EP equipment developed in the laboratory, a more detailed discussion is done about the treatment of the technical constraints like weigh measurement at elevated pressure (buoyancy). Advantage and limitation of the detailed equipment in term of result and potential studied are discussed. A preliminary study on cellulose pyrolyis at elevated pressure is presented. The work was done with commercial microcrystalline Sigmacell cellulose type 50 (30 mg) provided by Sigma-Aldrich, for pressure conditions between 0.1 MPa and 1 MPa, and at a constant heating rate up to 1000 °C. The inert atmosphere conditions were performed by carrying in constant nitrogen gas flow rate (30ml/ min). The results indicate a significant increase of the charcoal yield (>60%) compared to atmospheric condition results and suggest a significant involvement of secondary pyrolysis reactions.