N- Methyl thiomethyl phthalimide (I) a new compound was obtained when phthalimide was refluxed with DMSO acetic anhydride reagent and DMSO alone at 180 o C. A different route for the synthesis of N- Hydroxy methylphthalilmide (II)with excellent yield has also been explored by this reaction. Key Words : DMSO, Acetic anhydride, Phthalimide, Methyl thiomethylation