The title compound, C16H16N2O2, is a carbazole derivative with the 3-position substituted by a nitro group and the 9-position substituted by an n-butyl group. The nitro group is inclined to the benzene ring to which it is attached by 4.4 (2)°. The n-butyl substituent has an extended conformation and lies almost normal to the plane of the carbozole ring. In the crystal, inversion-related molecules stack along the a axis and are linked via offset π–π interactions, forming columns [shortest intercentroid distance = 3.773 (1) Å].
