Bio-oil is a the liquid phase obtained from the pyrolysis of biomass. The composition and amount of bio-oil generated depend not only on the type of the biomass but also on the conditions under which pyrolysis is performed. Most fossil fuels can be replaced by bio-oil-derived products. Thus, bio-oil can be used directly or co-fed along with fossil fuels in boilers, transformed into fuel for car engines by hydrodeoxygenation or even used as a more suitable source for hydrogen production than biomass. On the other hand, due to its rich composition in compounds resulting from the pyrolysis of cellulose, hemicellulose and lignin, bio-oil co-acts as a source of various value-added chemicals such as aromatic compounds.