Potentially tautomeric N-sulphonylformamidrazones and models with fixed amide- hydrazone and hydrazide-imide structure have been prepared. The compounds with tautomeric possibilities have been shown to exist only in the amide-hydrazone form by 13C and 1H NMR spectroscopy. The same compounds exist as two rotamers in solution arising hindered rotation around the N CH N single bond.