The benzimidazolone part of the title mol-ecule, C(17)H(25)N(3)O(3), is almost planar (r.m.s. deviation = 0.016 Å) and its mean plane is aligned at 7.9 (4) ° with respect to the mean plane of the nitro substituent. In the crystal, two mol-ecules are disposed about a center of inversion, generating a N-H⋯O hydrogen-bonded cyclic dimer with a R(2) (2)(8) graph-set motif.