The title compound, C13H15N5O, was synthesized by the reaction of 2-(1H-1,2,3-benzotriazol-1-yl)acetohydrazide with cyclopentanone. In the cyclopentane ring, two C atoms and their attached H atoms are disordered over two positions; the site occupancy factors are ca 0.63 and 0.37. In the crystal structure, molecules are linked into infinite chains directed along the b axis by N—H⋯O hydrogen bonds. In addition, there are weak C—H⋯O and C—H⋯N hydrogen bonds, as well as C—H⋯π-ring interactions in the structure