4-Methyl-5-phenyl-1H-pyrazol-3(2H)-one

The asymmetric unit of the title compound, C(10)H(10)N(2)O, contains two crystallographically independent mol-ecules with similar geometries, which exist in the keto form. The C=O bond lengths are 1.2878 (12) Å in mol-ecule A and 1.2890 (12) Å in mol-ecule B, indicating that the compound undergoes enol-to-keto tautomerism during the crystallization process. In mol-ecule A, the pyrazole ring is approximately planar [maximum deviation = 0.007 (1) Å] and forms a dihedral angle of 36.67 (6)° with the attached phenyl ring. In mol-ecule B, the dihedral angle formed between the pyrazole ring [maximum deviation = 0.017 (1) Å] and the phenyl ring is 41.19 (6)°. In the crystal, inter-molecular N-H⋯O hydrogen bonds link neighbouring mol-ecules into dimers generating R(2) (2)(8) ring motifs. These dimers are linked into ribbons along [101] via inter-molecular N-H⋯O hydrogen bonds, forming R(4) (2)(10) ring motifs.