The molecular structure of [4-((4-(tert-butyl)benzylidene)amino)-1,5-dimethyl-2-phenyl-1,2-dihydro-3H-pyrazol-3-one crystal and some physical and chemical properties were investigated using single crystal X-ray diffraction, FT-IR, UV and quantum mechanical methods. The compound studied in this study is the Schiff base compound and crystalizes in monoclinic space group I2/a. The molecule is not planar. The crystal structure is stabilized by intermolecular C-H…..π interactions. Theoretically, it was investigated using Density Functional Theory (DFT) and Hartree-Fock Roothann Method compared with the experimental results and it was seen that both results were in agreement with each other. In the DFT and HF calculations, the B3LYP / 6-31G +d base set and Berny's method were used.