4-Methoxypyridine N-oxide hydrate is a substituted pyridine N-oxide. It forms 1:1 complexes with MnCl2 and NiCl2 salts. Mechanism of reaction between 4-methoxypyridine N-oxide hydrate and bis(pinacolato) (diboron reagent) in CD3CN has been studied by NMR. It forms 1:1 complex with 2,4-dinitrophenol due to the formation of intermolecular hydrogen bond between the O-H and N-O groups.