4-Nitropyridine N-oxide has been reported as a quorum-sensing inhibitor, having IC50 value of 24μg/ml. Facile one-pot arylation and alkylation of 4-nitropyridine N-oxide has been reported. 4-Nitropyridine N-oxide can be prepared from pyridine by oxidation with peracetic acid and nitration. Primary photochemical process of 4-nitropyridine N-oxide has been investigated by steady-light irradiation and a flash spectroscopic method.