AbstractA comprehensive examination is made of the characteristics and quality requirements of bio‐oil from fast pyrolysis of biomass. An appreciation of the potential for bio‐oil to meet a broad spectrum of applications in renewable energy has led to a significantly increased R&D activity that has focused on addressing liquid quality issues both for direct use for heat and power and indirect use for biofuels and green chemicals. This increased activity is evident in North America, Europe, and Asia with many new entrants as well as expansion of existing activities. The only disappointment is the more limited industrial development and also deployment of fast pyrolysis processes that are necessary to provide the basic bio‐oil raw material. © 2012 American Institute of Chemical Engineers Environ Prog, 2012