Sulfur contamination has been a serious issue in oil industry so that desulfurization becomes a vital step in oil refinery to offer sulfur free products. The success of desulfurization requires disproportionation of sulfur‐containing molecules to form sulfur‐catenated compounds and further remove sulfur (S8). The reaction of ethyl acetate (EtOAc) with the gaseous components of products from the thermal decomposition of thiourea (condition 1) and the direct decomposition of thiourea in dimethyl sulfoxide (condition 2) provide two series of sulfur‐catenated molecules that have been characterized by gas chromatography‐mass spectrometry and partially by nuclear resonance spectroscopy with the help of ab initio calculation. This new method of in‐situ generating alkyl polysulfides might be applied to remove sulfur from the sulfur‐containing molecules in oil refining process to diminish the sulfur contents in oil products.