This article presents the results of study of dibenzothiophene (DBT, the fuel equivalence ratio $$\varphi = 0.94$$ –1.01) oxidation in a medium of dense water vapor or argon at uniform heating (1 K/min) to 853 K of a tubular reactor made of stainless steel. The oxidation of DBT was found to proceed by the mechanisms of heterogeneous and homogeneous reactions. From the dynamics of the temperature of the reaction mixtures it follows that self-ignition of DBT in an environment of water vapor and argon occurs at 532 K. A Pt-Rh/Pt thermocouple introduced into the center of the reaction volume was found to have a catalytic effect on DBT oxidation. The results of mass spectrometry analysis of gas products show that the degree of carbon burnout exceeds 95% mol. The interaction of stainless steel and H $$_{2}$$ SO $$_{4}$$ formed in the DBT oxidation in water vapor causes steel corrosion, which is suppressed due to neutralization of the acid by calcium carbonate. The composition of the corrosion products was determined by the X-ray diffraction and energy-dispersive analysis methods.