The reaction between dimethyl sulfoxide (DMSO) and chlorine was studied theoretically, using ab initio calculation in a high correlated level. A systematic study of reaction paths was conducted to address the role of the (CH3)(2)SO-Cl adduct formation. The channels that lead to CH3SOCH2 + HCl and CH3SOCI + CH3 will be relevant, and the global atmospheric rate constant was determined to be 1.2 x 10(-10) cm(3) molecule(-1) s(-1), at 298.15 K and 1 atm. The atmospheric implications of this reaction to DMSO chemistry also are discussed.