The current chapter presents a detailed of Fisher-Tropsch (FT) process to produce biocrude oil. FT process is a catalytic chemical reaction that convert the syngas, the mixture gas consists of hydrogen and carbon monoxide into liquid hydrocarbons. Biocrude oil, sometimes called bio-oil, is a synthetic fuel typically characterised by its dark colour, viscous consistency, and composition of numerous oxygenated organic compounds along with water. This chapter thoroughly explores the reaction mechanism of the FT process, including intermediate products and elemental reactions. Additionally, the operational conditions for both low- and high-temperature FT processes are discussed, together with the design considerations for FT reactors, catalysts, and the distribution of products. Biocrude oil produced from FT process has many applications in different areas include road, air, and marine transport sectors. In this regard, the commercial use of biocrude oil, its efficiency and performance also described in this chapter.