The generation of compounds derived from lignocellulosic biomass fractionation has a boost in recent years. An interesting plant could be tagasaste (Chamaecytisus proliferus) due to its high biomass production and its leguminous nature. A sequence of acid hydrolysis, as pretreatment, and pyrolysis of the solid residue, as treatment, has been used in its valorization. An experimental design (H2SO4 acid concentration 0.5–2%, temperature 130–170 °C, and time 30– 60 min) has been used to study the hydrolysis process. In the proposed acid hydrolysis process, under 170 °C as operational temperature, 0.5% of H2SO4 and 30 min for the operation time, 91.75% of the initial xylose have been extracted. The thermal behavior of both tagasaste trunks-large branches and some solid residues after hydrolysis (furthest and center points in the experimental design) process and raw material have been studied by thermogravimetric analysis under nitrogen atmosphere at different heating rates (5, 10, 15, and 20 °C min−1). The thermal degradation of the studied materials is influenced by its initial composition. Then, the higher reactivity of hemicelluloses can accelerate the pyrolysis degradation reaction. However, higher cellulose content implies lower activation energy in pyrolysis process.