It is necessary to reduce the amount of sulfur in fossil fuels due to direct impact of the quality of these fuels on the environment. In this research, a novel fungus strain of Exophiala spinifera, namely FM, was used to desulfurize dibenzothiophene (DBT) as a model cyclic sulfur compounds in oil and fossil fuels. HPLC analysis indicated that the fungus was capable of reducing 99% of DBT concentration in BSM medium after seven days. This fungus utilized DBT as a sulfur source by co-metabolism reaction with other carbon sources such as glucose. Exophiala spinifera was inoculated in BSM medium containing DBT with various carbon sources including ethanol, glucose, succinate, and glycerol. This fungus had the highest growth and desulfurization capability on glucose as a carbon source after 96 h. E. spinifera had best growth and desulfurization rates in 0.3mM DBT. Optimum DBT desulfurization and growth rate of this fungus was observed at 26-30 ^oC. Suitable pH for the optimum growth and desulfurization activity of E. spinifera strain FM ranged 4-5.