The products of reactions of styrene, phenylacelylene, and 1-bromo-1-phenylethane with HBr and Br2 in DMSO were studied for the first time by high-performance liquid chromatography and gas chromatography-mass spectrometry. Phenylglyoxal is the main product in the reactions with styrene and bromophenylethane, while dibromostyrenes are formed as the main products in the reaction with phenylacetylene. Schemes of the reactions of these substrates with the reagents are proposed. The reactions of nucleophilic addition and decomposition of the dimethylsulfoxonium salts formed are the key stages of the processes considered.