Molecular and crystal structure of 4-[(p-N,N-dimethylamino)benzylidene]-2-phenyloxazol-5-one, C18H16N2O2, have been determined by single crystal X-ray diffraction study. The title compound is monoclinic, with a = 12.1704(23) A, b = 3.9810(5) A, c = 30.9603(56) A, β = 101.176(15)°, Z = 4, D x = 1.32 g/cm3, μ(Mo Kα) = 0.087 mm−1, and space group is P121/c1. The structure was solved by direct methods and refined to a final R = 0.047 for 3166 reflections with I > 2σ(I). The crystal structure is stabilized by C–H⋯O and C–H⋯N type intra-molecular, C–H⋯O type inter-molecular interactions. To enlighten the flexibility and the geometric isomerism (E or Z) of the title compound, the selected torsion angle is varied from −180 to 180° in every 10° separately and molecular energy profile is calculated and analyzed. Molecular and crystal structure of 4-[(p-N,N-dimethylamino)benzylidene]-2-phenyloxazole-5-one, C18H16N2O2, have been determined by single crystal X-ray diffraction study, and then conformational analysis of the title molecule with respect to the selected torsion angle has been achieved by DFT using B3LYP hybrid functional.