Experiments have been carried out to determine the effects of biodesulfurization time on the removal of sulfur constituents of six Turkish lignites by Sulfolobus solfataricus. The changes in sulfur content of Tuncbilek, Karliova, Beypazari, Can, Elbistan, and Mengen lignites are shown as functions of time. A decrease in all sulfur forms with increasing time was observed for each coal. The highest total and organic sulfur reductions were observed with Beypazari lignite as 57.1 and 47.8%, respectively. The influence of analyses of the original samples on total and organic sulfur reductions has been investigated through multiple linear regression analysis. The resulting determination coefficients are compared to obtain the beat fitting parameter set. For the six lignites the experimental values of total and organic sulfur reductions appeared to agree with the values calculated for the models.