N′-(4-Hydroxy­benzyl­idene)isonicotinohydrazide

The title compound, C₁₃H₁₁N₃O₂, was prepared by the reaction of pyridine-4-carboxylic acid hydrazide and p-hydroxy­benzaldehyde in ethanol. In the crystal structure, all non-H atoms are coplanar, with an r.m.s. deviation of 0.096 Å. N—H...N, O—H...N and O—H...O inter­molecular hydrogen bonds stabilize the structure.