The thermal behaviors during the pyrolysis of two different biomass samples, beech wood from carpentry residuals and artichoke thistle from energy-dedicated crops, were investigated. Thermogravimetry/differential scanning calorimetry (TG-DSC) and thermogravimetry coupled to Fourier transform infrared (TG-FTIR) analysis of evolving products were used to investigate the thermal effects of the pyrolysis process. The role of pretreatments (hot-water washing, ethanol extraction, and their combination) was also analyzed. High alterations in the heat demand were observed as a function of the initial sample mass and pyrolysis conditions. The role of vapor-solid secondary interactions was evidenced by the evolution profiles of the main pyrolysis products.