Biomass generated from pruning of olive trees is an abundant lignocellulosic residue that has been proposed for bioethanol production by means of a process including pretreatment, enzymatic hydrolysis, and fermentation. The pretreatment is critical step in the process, which allows the fractionation of the biomass. Lignin is the main byproduct of the process, and then its valorization is a key factor for the economical viability of the bioethanol production from olive tree pruning. In this work, two types of pretreatments have been compared steam explosion and organosolv in terms of the produced lignin suitability for further applications in the so-called new biorefinery concept. Starting from this fact, special emphasis was given to determine the physico-chemical properties of lignins produced by the two processes in order to determine their suitability for the development of added value products (e.g. materials, building blocks, additives). Overall, the lignin obtained from organosolv pretreatment had better properties for its further valorization as it presents more suitable qualities for higher-added value applications like fine phenolic chemicals production.