The state of the art on fuel oxygenates, and in particular of MTBE in groundwater, is presented. Historically, oxygenates like MTBE were developed in the 1970s as octane enhancers to replace toxic additives like lead, which were phased out of gasoline. The presence of oxygenates in gasoline promotes cleaner fuel combustion within the engine, boosts fuel octane values and reduces vehicle emissions. Another relevant oxygenate is ethyl-tertiary-butyl ether (ETBE), which has increasingly replaced MTBE. Ethanol is by far the most commonly used alcohol oxygenate and bio-ethanol in particular is being increasingly used as a replacement for other fuel oxygenates. Today the discussion on the increase on corn production to produce bio-ethanol in order to reduce our dependency on oil is in the press. As a consequence corn cultivation started to increase in Europe, the US and Brazil with subsidiary plans from the governments up to 0.4 Euros/liter of biethanol produced. Other alcohols that can be used as fuel oxygenates are methanol and tertiary-butyl alcohol (TBA). TBA is, in addition, the main degradation product of MTBE and a potential impurity from the MTBE manufacturing process. This book deals mainly with the problems associated with the contamination of groundwater by MTBE and TBA, but ETBE is also considered. The book, written by recognized specialists in the field, is organized in sections covering state-of-the-art analytical methods, including specific isotopic analysis, occurrence in the environment, transport and degradation processes, treatment technologies and human health risks. It offers a unique opportunity not only for scientists who want to get more comprehensive information on this subject but also for policy makers and stakeholders that need to manage real-world environmental problems associated with fuel oxygenate contamination of our groundwater resources.