The title compound, 4-benzoyl-5-phenyl-1-p-methoxyphenyl-1H-pyrazole-3-carboxylic acid (C(24)H(18)N(2)-O(4)), was prepared from the reaction of 4-methoxyphenylhydrazine with 4-benzoyl-5-phenyl-2,3-dihy-dro-2,3-furandione, in good yield (63%), and characterized by IR, (1)H-NMR, (13)C-NMR and single-crystal X-ray diffraction (XRD) and elemental analysis. The compound crystallizes in the monoclinic space group P 2(1)/c with a = 10.9369 angstrom, b = 8.6306 angstrom, c = 23.7823 angstrom and beta = 102.461 degrees. Moreover, the molecular geometry from X-ray experiment, the molecular geometry, vibrational frequencies, gauge including atomic orbital (GIAO) (1)H and (13)C chemical shift values of the title compound in the ground state have been calculated by using the Hartree-Fock (HF) and density functional methods (B3LYP) with 6-31G(d) basis set. The results of the optimized molecular structure are exhibited and compared with the experimental X-ray diffraction. in addition to, molecular electrostatic potential (MEP) and frontier molecular orbitals (FMO) were executed by the B3LYP/6-31G(d) and PBEPBE/6-31G(d) method, respectively. Crown Copyright (C) 2010 Published by Elsevier B.V. All rights reserved.