The paper presents a study on the combustion of S-2 over a wide range of air/fuel ratios, employing numerical flame calculations, including a sulfur/oxygen reaction mechanism; reaction zone structures as well as the corresponding laminar burning velocities are reported. The numerical simulations are based on a detailed reaction mechanism derived from a H/O/S combustion mechanism from the literature after removing all reactions of hydrogen -containing species. Using reaction rate coefficients from the literature in the calculations brings about burning velocities in the order of magnitude of 300 cm s(-1) at T-0 = 373 K and under stoichiometric conditions. Sensitivity analysis of the computed results identified which reaction rate has crucial influence on the burning velocity and flame structure. It turned out that the sensitivity coefficients of burning velocity with respect to the rate coefficient of reaction S + O-2 -> SO + O are by far the largest sensitivity coefficients. Further investigations have been performed on the basis of different values of the rate constant of reaction S + O-2 -> SO + O taken from the literature and from our own calculations. The obtained significant changes in burning velocities as well as in species profiles elucidate the sensitivity of the burning velocity and flame structure on the magnitude of the reaction rate coefficient of this reaction and stress the importance of this reaction. This work constitutes a necessary and to be continued footstep toward a validated reaction mechanism for the combustion of sulfur.