Concern with environmental issues such as global climate change has stimulated research into the development of more environmentally friendly technologies and energy sources. One critical area of our economy is liquid transportation fuels. In response to these issues, Pure Energy Corporation has developed engineered fuels which are largely composed of chemicals which can be generated from renewable materials. This paper presents the results of biodegradability testing of these alternative fuels and their components and compares them to that of current fuels. Alternative fuels tested included: E85, biodiesel, B20, and two engineered fuels from Pure Energy Corporation (P-Series and OxyDiesel). Gasoline and #2 diesel (diesel) were also run as baseline comparisons. Determination of the biodegradability potential of the chemicals and fuel formulations was determined by using the ASTM Standard Test Method for Determining, Ready, Ultimate, Biodegradability of Organic Chemicals in a Sealed Vessel CO2 Production Test, ASTM Method E 1720-95. Performance data is also given for the two Pure Energy fuels and compared to gasoline and diesel. All alternative fuels tested proved to be more biodegradable than the hydrocarbon fuels, gasoline and diesel.