Ever since the 1970's algae have been proposed as a source of oils for transportation fuel production, and this interest has been renewed in recent years. Algae fix CO2 very efficiently and are capable of producing large amounts of oils that can be used for combustion engine fuel production. The freshwater green alga Botryococcus braunii produces long-chain liquid hydrocarbon oils in large quantities that can be converted into petroleum-equivalent fuels suitable for combustion engines. Additionally, B. braunii hydrocarbon oils have been found as major constituents of currently used petroleum and coal deposits. Recently, genes and enzymes for the biosynthesis of B. braunii oils known as botryococcenes have been identified, and many studies have assayed different culture conditions for effectively growing B. braunii. Business evaluations of a B. braunii oil production system suggest that it may become competitive in the fuel market by the midtwenty- first century. This chapter summarizes current knowledge on the biosynthesis, biochemistry and molecular biology, as well as cost analysis of hydrocarbon production in B. braunii.