Three N-oxides of Schiff bases (nitrones) with intramolecular hydrogen bonds were synthesized and studied by FTIR as well as 1 H and 1 3 C NMR methods. In the -O-H ON O H-ON intramolecular hydrogen bonds the protons fluctuate, whereas the weight of the O H-ON structure is low. In the FTIR spectra of these compounds very weak continua were found and explained by an electronically conjugation between donor and acceptor groups in the intramolecular hydrogen bond. Such bonds show almost no Zundel polarizability.