Lignin model fragmentation studies done in alkaline aqueous DMSO exhibited a high degree of β-aryl ether cleavage, a degree equal to that of a comparable soda/AQ system. Pulping studies with loblolly pine in aqueous DMSO demonstrated that DMSO accelerates delignification, but the quantities required appear Impractical. Several lignin model compounds have been heated at 150°C with alkali in aqueous DMSO to give complex product mixtures containing oxidation, reduction, and methyl sulfide addition products. Low temperature reactions of DMSO and dirasyl anion with in situ generated quinonemethides afforded unique products. Reactions attributed to DMSO were not observed when an oxidized analog, dimethylsulfone, was substituted for the DMSO.