The present invention relates to a process for preparing sulfur-containing compounds of the general formula I in which Q, R1 and R2 are each independently defined as follows: Q: —S— or —S—S—, R1: hydrogen or saturated or unsaturated, linear or branched C1-C30-alkyl radical, R2: hydrogen or saturated or unsaturated, linear or branched C1-C30-alkyl radical, where R1 and R2 are not simultaneously hydrogen, by reacting a mixed gas stream comprising hydrogen sulfide, with or without oxygen, with linear or branched C1-C30-olefins, which comprises carrying out the reaction in the presence of water and carbon dioxide at a pressure of from 2 to 325 bar.