Polysulfide anions react with α,β unsaturated aldehydes in aquatic media. Michael addition mechanisms control the first step, which follows the same pathway as in phase transfer catalysis (PTC) systems. The end products are polysulfide cross-linked oligo-polymers. The kinetic profiles, measured by 1H NMR and elemental analysis, changed dramatically with the length of the carbon skeleton. The reaction rates are controlled by the concentration of both polysulfides and the substrate. A comparative study revealed the importance of the cation (e.g., sodium or ammonium) and pH conditions, as controlling factors. The mechanism proposed is further elucidated by the detailed study of MeLi/MeI degradation products release from the oligo-polymers formed. These results are important in increasing our understanding the role of polysulfides in sulfur enrichment of organic matter in marine environments.