Pseudomonas C12B (NCIMB 11753) is able to utilize a broad range of alkyl sulfates. The growth on n-alkanes of different chain lenght (C-6-C-16) was tested. Pseudomonas C12B assimilated hydrocarbons from C-9-C-16. Growth rate on n-decane (1%) that was chosen as the typical sole source of carbon and energy depended on oxygen supply. The addition of surfactants (Triton X-100 and Tween-80) in a nontoxic concentrations resulted in increased biomass yield. Under optimal growth conditions Pseudomonas C12B exhibited the maximal growth rate and yield with C-11 as the sole carbon source.