(4Z)-4-[(2E)-1-Hy-droxy-3-(3-nitro-phen-yl)prop-2-en-1-yl-idene]-3-methyl-1-(4-methyl-phen-yl)-1H-pyrazol-5(4H)-one.

In the title compound, C(20)H(17)N(3)O(4), the dihedral angles between the heterocyclic ring and the toluene and nitro-benzene rings are 4.21 (15) and 11.43 (14)°, respectively. The whole mol-ecule is close to planar (r.m.s. deviation for the 27 non-H atoms = 0.171 Å). Two S(6) rings are formed due to intra-molecular C-H⋯O and O-H⋯O hydrogen bonds. In the crystal, inversion dimers linked by pairs of C-H⋯O bonds generate R(2) (2)(10) loops and further C-H⋯O bonds link the dimers along the b-axis direction. There exist π-π inter-actions between the heterocyclic rings at a centroid-centroid distance of 3.7126 (10) Å and between the centroids of the benzene rings at a distance of 3.8710 (16) Å.