The most significant aspects of the knowledge of the fast biomass pyrolysis are collected in this chapter, with the objective of analyzing bio-oil production (fast pyrolysis) and its valorization for the production of fuels and raw materials. Attention is focused on the aspects of applied interest for the large-scale implementation of fast pyrolysis by analyzing the effect of reaction conditions, features of alternative reactors, and the state of the art of different technologies. The authors have also examined the initiatives for improving pyrolysis in order to condition bio-oil properties for direct use as fuel or for its subsequent valorization, and to reduce the operating limitations and energy requirements (using in situ cracking and deoxygenation catalysts, vacuum operation, microwave heating, or oxidative pyrolysis). In addition, this work updates the integration of pyrolysis with an in-line catalytic conversion stage of oxygenated volatiles, focused on the production of either H2 (reforming catalyst) or light olefins or BTX aromatics (with HZSM-5 zeolite catalysts). Among the alternatives for bio-oil valorization, emphasis has been placed on the catalytic processes and the bio-oil role as H2 vector for the production of light olefins or aromatics, as well as raw materials to be introduced in refinery units, such as in fluid catalytic cracking (FCC) units, together with other oil-derived streams.