One dozen of tailormade model 3-fluoro-2(1H)-quinolinones were synthesized, in order to be investigated by UV-, IR- and NMR spectroscopic techniques. All of these compounds were found to exist predominantly, if not exclusively, in the lactam (carboxamide, 1,2-dihydro-2-oxoquinoline) form. No tautomeric lactim (iminol, azaphenol) structure was detected. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008).