Biodesulfurization is a microbial biocatalytic process that removes sulfur from hydrocarbons. Because this bioprocess can be influenced by substrate bioavailability, we studied the effect of natural and synthetic surfactants on biodesulfurization using metabolically active and immobilized bacterial cells. Surfactants are surface-active molecules that improve the solubility of solids or water insoluble substrates. Metabolically active cells of the desulfurizing strain Rodococcus rhodochrous IGTS8 were immobilized on Silica (Si), Alumina (Al) and Sepiolite (Sep) by adsorption. The desulfurization activity was determined in the presence of biological and synthetic surfactants. The results indicate that adding surfactants to the catalytic system formed by non-immobilized or immobilized cells increases desulfurizations of DBT and gas oil. A major effect was observed when a microbial biosurfactant was used to improve the interaction between insoluble sulfured substrates and the respective immobilized biocatalytic systems. The bioavailability of the sulfured substrates improved because of micelle formation. The use of a biocatalytic system conformed by immobilized cells; biological surfactants and sulphured substrates can be an improvement methodology for BDS makes more feasible a potential application on industry. (C) 2013 Elsevier Ltd. All rights reserved.