Clostridium thermocellum has the ability to ferment cellulose into ethanol, making it a promising bacterium for lignocellulotic based bio-fuel production. The purpose of this project was to optimize the currently used low carbon (LC) media for C. thermocellum cultivation. An optimized media would allow for high density cultivation, optimization of growth conditions and provide a more effective use of resources. Additionaly, an optimized media would give opportunities for more pilot experiments and in the long run contribute to the large scale production of lignocellulotic based bio-fuel production. To optimize the LC media, limitation of eleven nutrients were tested individually: nitrogen, phosphate, sulfate, iron, potassium, calcium, magnesium as well as the four essential vitamins pyridoxamine, para-aminobenzoic acid (PABA), biotin and B12. For each nutrient a range of six different concentrations were tested, the purpose was to find the linear relationship between limiting concentrations and OD₆₀₀ for C. thermocellum. Results of concentrations per OD₆₀₀ could be compiled for nitrogen (2.23 - 2.72 mM/OD600), phosphate (75.1 - 81.7 μM/OD₆₀₀), sulfate (0.182-0.526 mM/OD₆₀₀) and iron (0.218 - 0.405 μM/OD₆₀₀). No linear correlation between concentration and OD₆₀₀ was found for the remaining seven nutrients. However, the obtained data can prove useful in future experiments to give an idea of what ranges should be tested for a specific nutrient. The results suggests that potassium should be tested in the range 0.5-1 mM, calcium above 40 μM and magnesium below 0.5 mM. Further, the obtained results showed that C. thermocellum could grow mostly unhindered for all tested vitamins for all concentrations, these should be tested in lower concentrations in future experiments.