Abstract: The dimethyl sulfide(DMS) was irradiated by UV in the absence or presence of O₂ and H₂O₂.The products of photolysis were detected by a Fourier Transform Infrared Spectroscopy equipped with a 20m long path cell. The results indicate that the C─S bond of DMS could be broken in the absence of O₂. As a result, CH₃SSCH₃ and CH₃CH₃ compounds were formed. In the case of presence of O₂ in the system,CH2O and CH₃SO_H could be formed. If H₂O₂ presents in the system, the products of photolysis of DMS would be CH₃SO₃H and CH₃SSCH₃. The mechanism of photolysis of DMS has been discussed. According to this mechanism, the formation of products can be explained.

Key words: dimethyl sulfide, FTIR, UV photolysis