The crystal structure of the title compound, C11H10N4, comprises molecules in a trans conformation for which all the atoms are located in general positions. The six-membered rings are coplanar and this arrangement might be stabilized by intramolecular N—H...N hydrogen bonding. In the crystal, the molecules are linked into helical chains parallel to the b axis via N—H...N hydrogen bonding. The molecular packing shows a herringbone-like pattern along the a axis. Comparison of the X-ray powder diffraction with that calculated from single crystal data proves that a pure crystalline phase was obtained and UV–Vis measurements reveal that only the trans isomer is present.