AbstractAdhesive-free fiberboards can be self-bonded through high temperature thermo-compression processes. To achieve it, treatments such as steam explosion/injection, as well as chemical and enzymatic oxidation have been implemented. However, the role of extractive components in the structure and cohesiveness of fiberboards has not been fully understood. In this work fibers of leaf plantain were treated with organic solvents and with hot water to remove the extractives, and were then employed to produce self-bonded fiberboards. Treated fibers were characterized by thermogravimetric analysis, electronic paramagnetic resonance, and antioxidant capacity. The mechanical strength of the fiberboards evaluated by three point flexural tests, decreased when fibers were extracted with aqueous solvents, and increased after treatment with organic ones. This can be explained by the effect of water extractives in reducing the initial degradation temperature, and in retaining free stable radicals generated during thermo-compression. In the case of the organic extractive fraction, this inactivates the fibers, which impairs close contact between polar groups and thus decreases the mechanical properties of the fiberboards. According to the results, it is possible to increase the mechanical properties of self-bonded fiberboards by changing the concentration of polar and low molecular weight phenolic compounds.