Desulfurization of dibenzothiophene (DBT) by whole cells of Rhodococcus erythropolis H-2 proceeded efficiently in the presence of two model petroleums-kerosene or a mixture of hydrocarbons, The reaction Fate was enhanced by the addition of these model petroleums at 40 and 20%, respectively. The optimal temperatures for the degradation of DBT and the formation of 2-hydroxybiphenyl (2-HBP), tile DBT desulfurization product, were 45 degrees C and 40 degrees C, respectively, which were higher than the upper temperature limit (37 degrees C) for growth with DBT as a sole source of sulfur, These results are evaluated from the viewpoint of practical microbial desulfurization.