The title compound, C(10)H(15)N(3)O, crystallizes in an infinite two-dimensional polymeric network due to inter-molecular N-H⋯O hydrogen bonding. Intra-molecular N-H⋯N and inter-molecular C-H⋯N inter-actions are also present. The 3,4-dimethyl-phenyl unit is disordered over two sites with an occupancy ratio of 0.677 (5):0.323 (5). The dihedral angle between the benzene rings of the disordered components is 2.6 (6)°.