The title compound 3-amino-5-(4-chlorophenyl)pyridazine-4-carbonitrile was prepared by a one-pot three-component reaction of malononitrile with corresponding arylglyoxal in the presence of hydrazine hydrate at room temperature in water and ethanol. Its structure was also con?rmed by its IR, 1H, 13C-NMR, Mass spectral data and elemental analysis. The compound was crystallized in the monoclinic system, space group P21/c, a = 3.817(3) ?, b = 13.533(10) ?, c = 19.607(15) ?, B = 93.401(10)°, Z=4, R1 = 0.0906 and wR2 = 0.1422. The crystal structure of the compound also shows a weak intermolecular interaction between N1 atom of one molecule and N3 atom of the other molecule.